Damped spacer articles and disk drive assemblies containing damped spacer articles

ABSTRACT

The present invention relates to a vibration damped spacer articles having good force (torque and/or pressure and/or stress) retention, and disk drives having a damped spacer article and a rotatable storage article inserted therein.

[0001] This application is a divisional application of co-pending U.S.patent application Ser. No. 09/108,981, filed Jul. 1, 1998, the entiretyof which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to a vibration damped spacerarticle, the spacer article preferably having good force (torque and/orpressure and/or stress) retention and the ability to provide damping toan adjacent rotatable storage article on a disk drive assembly. Thepresent invention provides a damped spacer article that preferably has asufficient force retention to prevent significant rotatable storagearticle movement during use. The present invention also provides a diskdrive having rotatable spacer article(s) and the damped spacerarticle(s) positioned thereon.

BACKGROUND OF THE INVENTION

[0003] Periodic or random vibrations or shocks can excite the resonantfrequencies in a rotatable storage article (such as the disk(s) in adisk drive), which can be problematic due to the resultant formation ofundesirable stresses, displacements, fatigue, and even sound radiation.Such undesirable vibrations or shocks are typically induced by externalforces and can be experienced by a wide variety of articles and under avariety of conditions. For example, resonant vibrations can causeexcessive vertical displacement of an optical disk's surface duringoperation, which may lead to poor laser focus. Proper laser focus is akey to optimum write/read characteristics, signal quality, and trackingability.

[0004] Various techniques have been used to reduce vibrational and shockeffects (stresses, displacements, etc.) on rotatable storage articles.Three basic techniques to reduce vibration and shock effects include:

[0005] 1) adding stiffness or mass to the rotatable storage article sothat the resonant frequencies of the rotatable storage article are notexcited by a given excitation source,

[0006] 2) isolating the rotatable storage article from the excitationsource so the vibrational or shock energy does not excite the rotatablestorage article's resonant frequencies, and

[0007] 3) damping the rotatable storage article so that givenexcitations from the excitation source do not result in excessivenegative effects at the resonant frequencies of the rotatable storagearticle.

[0008] An isolation technique for limiting vibration transmission isdescribed in U.S. Pat. No. 4,870,429. A single-sided or double-sidedoptical disk structure is described that includes two sheets ofsubstrate bonded to each other with a foam spacer interposed between thetwo substrates to restrict or isolate the vibrations caused by externalforces. The spacer is made from an elastomeric foam material and ispositioned between the two substrates to restrict the transmission ofsuch forces (e.g., vibrations or shocks). The thickness of the spacer isstated to be preferably not less than 0.2 mm, more preferably not lessthan 0.4 mm, because, when the thickness is too small, the effect of thespacer to restrict or isolate forces is not exhibited sufficiently. Sucha system adds to the overall size of the rotatable storage article andmay be impractical where close positioning of the article to otherstructures is desired.

[0009] Two types of surface or external damping treatments that can beused to reduce shock or vibration impact on rotatable storage articlesare: (1) free layer damping treatments; and (2) constrained layerdamping treatments. Both of these damping treatments can provide highlevels of damping to a structure, i.e., dissipation of undesirablevibrations, without sacrificing the stiffness of the structure. The useof viscoelastic materials as exterior surface damping treatments isdescribed in EP 0507515. Examples of additional surface or externaldamping techniques are described, for example, in U.S. Pat. Nos.2,819,032; 3,071,217; 3,078,969; 3,159,249; and 3,160,549. However, allof the aforementioned damping techniques can add complexity and expenseto the design of the rotatable storage article, limit the amount ofexterior article surface available for data storage, and can increasethe overall size of the article.

[0010] U.S. Pat. No. 5,725,931 discloses a constrained layer damperhaving slits and/or cutouts therein, which constrained layer damperprovides improved damping performance. The constrained layer damper isuseful for damping rotatable storage media, such as compact disks.

[0011] U.S. Pat. No. 5,691,037 and WO 96/21,560 disclose vibrationdamped laminate articles having improved force (torque and/or pressureand/or stress) retention, a method of making one article type, and noveltools used to make the one article type. The first laminate comprises atleast one layer of damping material between at least two substratelayers. At least one deformation area is present in the laminate wherethe substrates are plastically deformed such that they are closertogether than in non-deformed areas of the substrate and the dampingmaterial has less mass than in a non-deformed area of the article. Thedeformation area provides areas of good force retention for anattachment device attached thereto. The second laminate, which is notdeformed, contains an additive of sufficient modulus, diameter andloading in its vibration damping layer to provide improved forceretention. Spacer articles for disk drives are not discussed.

[0012] U.S. Pat. No. 5,538,774 provides a method for internally dampinga rotatable storage article that is subject to resonant vibrations. Therotatable storage article, although capable of providing good damping,requires a redesign of the rotatable storage article to include theinternal damping material, which can be costly to manufacture.

[0013] The typical method of providing spacing between disks in a diskdrive type application involves the use of solid spacers between thedisks. These spacers can be made from many materials, includingaluminum, ceramics, stainless steel, rigid plastics, etc. These spacers,however, provide minimal vibration damping.

[0014] As the read and write tracks per inch (TPI) and the recordingdensity of disks increase, there is a need to improve the vibrationdamping of disks economically and simply to implement the disks inexisting and future disk drives. With new recording head technology,higher TPIs are possible (10,000-100,000 TPI and above). This now makesvibrations in disks more important to reduce, as vibrations in disks canreduce the TPI that can be reliably read and written. In the past, thespacers have been used to space the disks apart and provide someisolation or improved thermal expansion properties to prevent disks,such as ceramic disks, from breaking.

[0015] For example, U.S. Pat. No. 5,663,851 discloses a disk drivespindle hub assembly for a hard disk drive that includes a spindle hubwith a stack of information storage disks journaled about the spindlehub in a spaced-apart, vertically aligned relation. Annular spacers arepositioned between adjacent information storage disks in order to spacethe disks apart in the vertically aligned relation of the spindle hub. Adisk clamp is configured to concentrically clamp the stack ofinformation storage disks in axial alignment with the spindle hub. Adummy disk comprising an arrangement of a metal plate, a dampingportion, and a polyester film is disposed between the disk clamp and thestorage disk in order to absorb spurious vibrations and minimize stressconcentrations and disk distortion when the storage disks are mountedfor rotation within the hard disk drive.

[0016] Newer drive rotation speeds of 7,200 and above revolutions perminute (RPMs) plus increased shock requirements (500 to 1,000 or more gof force) require a high force retention in the spindle assembly toprevent disks from slipping or shifting on the spindle. Shipping orshifting can cause data location to be lost or degraded, hinderingread/write performance and/or drive reliability.

[0017] U.S. Pat. No. 5,367,418 discloses a hub assembly thatincorporates O-rings that can absorb external loads applied in either anaxial or radial direction relative to the hub.

[0018] U.S. Pat. No. 5,590,004 discloses a resilient clamping memberpositioned between a spindle flange and the upper side of a disk, with acompliant element supported by the spindle rim and contacting the lowerside of the disk.

[0019] U.S. Pat. No. 4,945,432 discloses a spacer design that serves asa buffer when the magnetic disks and the spacers are compressedtogether. The substrates of the magnetic disks are made of non-metallicmaterials, such as glass or ceramics, but do not break easily by themotion of the spindle or the change in temperature because either the 1)adhesive used to form a unistructural assembly of the magnetic disks or2) spacers or elastic members inserted in annular indentations formed inthe spacers serve as buffers when the magnetic disks and the spacers arecompressed together.

[0020] U.S. Pat. No. 5,422,768 discloses a compliant hard disk assemblyfor a recording/reproducing device. According to the abstract, tominimize unwanted motion in a hard disk assembly in a hard disk drive,an elastomeric support is employed to mount a hard disk pack forrotation by a motor rotor of a disk spindle motor. The hard disk packincludes a hard disk support ring that has opposite annular axial facesupon which the hard disks are securely mounted and axially spacedthereby. An elastomeric connection between the hard disk support ringand a cylindrical body of the motor rotor of the disk spindle motorprovides a soft, or compliant, support for the hard disk pack.

[0021] A need exists for a spacer articles that address the needs ofnewer hard disk drives that have higher TPIs (greater than 10,000 TPI,typically 17,000 or more TPI) and higher RPMs (greater than 5,000 RPM,typically 7,200 RPM or higher) that lead to more disk vibrations asdrive disk capacity increases. There is also a need for thinner disks toallow more disks in a drive format height. The disks need to beadequately damped to provide a minimally vibrating surface for readingand writing information or the drive will not be able to perform at thenext level of capacity that is now needed to meet growing industrydemands for a low cost megabyte of memory.

SUMMARY OF THE INVENTION

[0022] Although internally damped rotatable storage articles asdisclosed in U.S. Pat. No. 5,538,774 are very useful, it is not alwayseconomically feasible to provide all such articles with an internaldamping material. Articles that do not have such internal dampingmaterial still require some kind of damping. Furthermore, rotatablestorage articles that are internally damped may still benefit fromadditional damping.

[0023] Metal spacer rings, and the various drive designs described inthe aforementioned patents, although providing at least some damping,may not provide as much damping as one would desire to meet the everincreasing needs for a more stable read/write disk surface.

[0024] Damped spacer articles of the invention can be used with bothdamped and undamped rotatable storage articles and are capable ofproviding excellent damping properties as well as good force retention.The spacer articles are preferably capable of providing avibration-resistant disk drive assembly. Preferably the spacer articleallows a rotatable storage article to maintain its shape and will notdistort the typically flat rotatable storage article. Preferably thespacer article experiences little or no outgassing of components thatcould interfere with the drive reliability. Preferably the spacerarticle provides high force retention. The spacer articles arepreferably designed such that the vibration damping material containedtherein does not readily become squeezed out when a force is appliedthereto.

[0025] Optionally, a spacer article further comprises in its vibrationdamping material an effective amount of an electrically conductivematerial so that the resistance between substrates is less than about100 ohms.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 illustrates a top view of a spacer article of theinvention.

[0027]FIG. 2 illustrates a cross-sectional view of the spacer article ofFIG. 1.

[0028]FIG. 3 illustrates a cross-sectional view of another embodiment ofa spacer article of the present invention.

[0029]FIG. 4 illustrates a cross-sectional view of another embodiment ofa spacer article of the present invention.

[0030]FIG. 5 illustrates a cross-sectional view of a disk drive assemblyof the invention.

[0031]FIG. 6 illustrates a cross-sectional view of a spacer article ofthe present invention.

[0032]FIG. 7 illustrates an exploded view of the disk drive assembly ofFIG. 5.

[0033]FIGS. 8, 8a, 9 and 10 are side views of different embodiments ofprior art punches useful in making an embodiment of the spacer articleof the present invention.

[0034]FIG. 11 is a bottom view of a prior art punch useful in making anembodiment of a spacer article of the present invention.

[0035]FIG. 12 is a partial cross-section of a prior art punch useful inmaking an embodiment of the spacer article of the present inventiontaken along line 12-12 of FIG. 11.

[0036] FIGS. 13-34 illustrate partial cross-sectional views of otherembodiments of spacer articles of the present invention.

[0037]FIG. 35 illustrates a cross-sectional view of another embodimentof a spacer article useful in the disk drive assembly of the presentinvention.

[0038]FIG. 36 illustrates a schematic of the testing set-up formeasuring vibration damping performance of the spacer articles in a diskdrive assembly.

[0039]FIG. 37 illustrates an expanded view of a portion of the schematicof the testing set-up of FIG. 36, which shows primarily the spindleassembly from a disk drive.

[0040]FIG. 38 illustrates a graph showing the modes of vibration(frequency versus magnitude) for various rotatable storage articlesdescribed in the Examples.

[0041]FIG. 39 illustrates a graph showing the spacer article performancecomparison of temperature versus Root Mean Square (RMS) displacement forvarious rotatable storage articles described in the Examples.

[0042]FIG. 40 contains data for the graph in FIG. 39.

[0043]FIG. 41 illustrates a graph showing the spacer article performancecomparison of force retention versus time for various damped spacerarticles in the Examples.

[0044]FIG. 42 contains data for the graph in FIG. 41.

DEFINITION OF TERMS

[0045] The term “attachment device” as used herein refers to items suchas screws, bolts, clamps, nails, rivets, clamp/screw combinations,integrally molded attachment devices and other mechanical attachmentdevices that can hold the spacer article(s) along with the rotatablestorage article(s) in a desired location, position, altitude orconfiguration with a desired level of stress and/or torque and/orpressure and/or force.

[0046] The term “means for securing the rotatable storage article andspacer article onto the spindle” includes, for example, attachmentdevices as well as heat shrinking.

[0047] The term “force application area” as used herein describes thearea in which an article such as an attachment device, a rotatablestorage article, another spacer article, etc., may contact the spacerarticle and impart a force (i.e., holding force) that is used to holdthe spacer article in a position, location, altitude, or configuration.

[0048] An example of a “force application area” is an area of the spacerarticle under the flange of a clamp that in turn has force applied to itby a head of a screw which is directly above it, for example, the “forceapplication area” being defined to extend through the entire spacerarticle.

[0049] The term “deformation area” as used herein describes a section ofan article in which at least one substrate layer has been plasticallydeformed. The deformation area includes any article layer areas aboveand below the plastically deformed substrate areas. The deformation areais defined such that it does not include a through hole.

[0050] The force application area can be the same as, larger or smallerthan the deformation area for the embodiment of the spacer articlehaving a deformation area, when a deformation area is present in thespacer article. The deformation area is generally designed to be assmall as required to meet the needs of the attachment device so as tohave a minimal impact on the performance of the laminate spacer articlein terms of resonant vibration control and noise generation ortransmission.

[0051] The terms “residual spring effect” and “residual spring force”are used interchangeably herein to refer to the spring-type potentialresistive force that exists between two or more substrate layers of alaminate that have a separation between them. This separation willrequire the attachment force of the attachment device to overcome theresidual spring force during attachment device application. Substratelayers that are deformed such that no, or minimal, separation existsbetween the substrate layers will have no, or insignificant, residualspring force to overcome.

[0052] The term “spring back” as used herein refers to the tendency ofthe laminate substrate layers of deformed spacer articles to act assprings when put under a load. The substrate layers may be formed in amanner so that when force is applied to them, they are under stress.When the stress is removed, they will spring back at least partially totheir initial position.

[0053] The terms “damped laminate” and “laminate” are usedinterchangeably herein to refer to a construction comprising at leasttwo substrate layers and at least one layer of a vibration dampingmaterial comprising a viscoelastic material that has a lower storagemodulus than the substrate layers it is positioned between. The laminatecan also be of a multiple layer construction that may have more than twosubstrate layers and also more than one vibration damping materiallayer. The construction could also have vibration damping materiallayers adjacent to each other in layers or stripes or other patterns.The vibration damping material layers may be continuous ordiscontinuous. A discontinuous layer may be separated by space(s) and/ora nondamping material. A continuous layer may comprise the same dampingmaterial or different damping materials adjacent to each other, therebyforming a continuous surface. The substrate can comprise the samematerial or different substrate materials.

[0054] The terms “plastically deformed” and “plastic deformation” areused herein to describe the permanent change to a laminate's shape,profile, contour, or features that occurs when the substrate layers areexposed to: 1) a force or strain (typically from a punch tool and thetool's working surfaces) that imparts a force into the substrates thatexceeds the substrates' yield strength and/or 2) to heat.

[0055] The term “rotatable storage article” as used herein refers to amedia that has information stored on it and/or that is capable ofstoring information. The article is typically capable of being rotatedin some manner that allows the data stored on the article to be passedby a read or write element to allow reading of information from thearticle, or writing of information on the article, or both. Examples ofstorage articles include rigid disk drive disks, optical disks, compactdisks (CDs), magneto-optical disks, records, drums, floppy disks and thelike.

[0056] The term “spacer article contact surface” as used herein refersto the surface area(s) of the spacer article that an article above thespacer article comes into contact with, such as an attachment device,rotatable storage article, another spacer article, etc. and imparts theattachment device's force upon the spacer article.

[0057] A “through hole” as used herein refers to a hole that passescompletely through an article. The term “through hole” as used herein ismeant to include both completely enclosed through holes such as would beprovided, for example, by a spacer article having a shape similar to theletter “o” and a partially enclosed through hole, which may have a shapesimilar to the letter “c,” for example. A spacer article that has ashape that provides a completely enclosed through hole would be moretypical. However, a spacer article that has more of a “c” shape and thatdoes not provide a through hole that is completely enclosed may also beuseful. The substrate and/or vibration damping material portion of aspacer article may, optionally, be broken, grooved, beveled, segmented,slotted, split, or non-continuous, as long as the spacer article hasstructural integrity and encompasses a through hole. For example, if thespacer article is a laminate with several substrate layers, onesubstrate layer may be segmented in such a way as not to affect thestructural integrity of the article.

[0058] The term “working surface(s)” as used herein refers to thesurfaces area(s) of a punch tool that come into physical contact with alaminate during the punch tool stamping operation when providing one ofthe spacer article embodiments of the invention.

[0059] The term “offset” as used herein refers to when: (1) the uppersurface of the first substrate and the upper surface of the secondsubstrate of a nested substrate spacer article are not level, (2) thelower surface of the first substrate and the lower surface of the secondsubstrate are not level, and (3) if the substrates are of unequalheights, the shorter substrate is positioned such that its upper surfaceextends above the upper surface of a taller substrate or such that itslower surface extends below the lower surface of the other substrate.

[0060] The term “disk drive” as used herein refers to devices that arecapable of rotating rotatable storage articles (such as a compact disk,for example) in a manner that information may be retrieved from and/orprovided thereon. Examples of these devices are CD-ROM drives, floppydrives, removable media drives, rigid disk drives, optical drives,magneto-optical drives, magnetic drives, DVD disk drives, and the like.

[0061] A “partial cross-section” with respect to a spacer article of acomponent thereof is the cross-section taken from the center of thethrough hole towards an outer perimeter of the article or component.

[0062] A “configuration in partial cross-section that is U-shaped” isdefined as a cross-section taken from the center of the through holetowards an outer perimeter of the spacer article. The U-shape may, forexample, be angular or rounded. It may also be sideways, right-side-up,or upside-down.

[0063] A “sideways U-shape in partial cross-section” refers to across-section taken from the center of the through hole towards an outerperimeter of the spacer article. The sideways U-shape may, for example,be angular or rounded.

DETAILED DESCRIPTION OF THE INVENTION

[0064] Various embodiments of useful spacer articles and disk drives aredescribed herein.

[0065] Spacer Articles

[0066] A number of spacer articles are laminates or include a laminateas a component thereof. These spacer articles include, for example, thespacer articles referred to herein as press-fit laminate spacerarticles, deformed spacer articles, particulate/fiber containing spacerarticles, welded spacer articles, and high modulus vibration dampingmaterial laminate spacer articles.

[0067] A laminate is prepared from an upper substrate layer (which istypically flat) and a lower substrate layer (which is typically flat)and at least one layer of vibration damping material comprising aviscoelastic material positioned between the upper and lower substratelayers. The substrate layers have a higher storage modulus than theviscoelastic material in the vibration damping material.

[0068] A wide variety of shapes are possible for the spacer articles.Each spacer article is typically circular in shape (although it may beoval, rectangular, etc). The outer and/or inner perimeter of the spacerarticles may optionally be notched, jagged-edged, slotted, hatched,contain protrusions, etc. The spacer article is typically ring-shaped,as well as each component making up the spacer article (such assubstrates, vibration damping material, and laminate made therefrom,etc.).

[0069] Each spacer article discussed herein has a diameter. The diameterof each spacer article typically ranges from about 1 to about 300 mm,preferably about 5 to about 100 mm, and most preferably about 10 toabout 70 mm.

[0070] Each spacer article has a through hole. Each substrate layer (aswell as each vibration damping material layer and laminate) also has athrough hole positioned therein. The through hole may have a widevariety of shapes. Typically the through hole is a circular through holethat is centrally positioned therein, although it may be oval,rectangular, etc. Typically the through hole diameter ranges from about0.5 to about 299.9 mm, preferably about 4.9 to about 99.9 mm, and mostpreferably about 9.9to about 69.9 mm.

[0071] Each substrate layer is typically identical in dimensions andcomposition, although they may vary. For example, each substrate layermay vary as to thickness, diameter and/or topography, etc.

[0072] Each substrate layer is typically circular in shape (although itmay be oval, rectangular, etc.). The outer and/or inner perimeter ofeach substrate layer may, optionally, be notched, jagged-edged, hatched,contain protrusions, etc. The two section spacer articles discussedherein, although including an inner vibration damping material layer,differ in that their substrate layers are not flat, but typically LandT-shaped.

[0073] Typically each substrate layer has a length or diameter of about1 to about 300 mm, preferably about 5 mm to about 100 mm, and mostpreferably about 10 mm to about 70 mm. Each substrate layer typicallyhas a thickness of about 0.01 mm to about 25 mm, preferably about 0.05to about 10 mm, and most preferably about 0.5 to about 5 mm.

[0074] Typically the thickness ratio of the upper and lower substratesranges from about 1:1 to 1:20, preferably about 1:1 to about 1:5, evenmore preferably about 1:1 to about 1:1.5, and most preferably about 1:1.

[0075] The thickness of the vibration damping material layer typicallyranges from about 0.001 to about 5 mm, preferably about 0.01 to about 1mm, and most preferably about 0.02 to about 0.5 mm.

[0076] The spacer articles of the invention typically contain at leastone vibration damping material layer or component, more typically 1-3layers, preferably 1-2, and most preferably one layer, for reasons ofsimplicity of the article's manufacturing process and cost. Stiffnessmay also be sacrificed when more than one damping material layer orcomponent is included. However, a wider temperature range of damping ispossible when multiple layers of different vibration damping materialsare included. Sufficient damping material should be used to obtain thedesired damping effect, while balancing the structural requirements ofthe article.

[0077] Substrate Material

[0078] Each spacer article comprises a substrate. Substrates, such assubstrate layers, substrate rings, substrate sections, substratecomponents, etc. useful in the article of the invention can be anymaterial having a higher storage modulus than the viscoelastic materialof the vibration damping material of the spacer article. Typicalsubstrate materials have a Young's modulus greater than about 5×10⁵ psi(34.5×10⁸ Pascals) at the operating temperature of the application(typically about −60 to 100° C.). Examples of suitable substratematerials include, but are not limited to, those selected from the groupconsisting of stainless steel, aluminum, aluminum alloys, copper, carbonsteel, lead, glass, ceramics, polyethylenes, polyolefins,polycarbonates, polystyrenes, polyimides, polyesters, polyacetates,vinyl copolymers, poly acetals, and phenolics. The substrate may,optionally, be coated with a coating, such as paint, etc.

[0079] In the case of the plastically deformed spacer article, at leastone substrate must be capable of being plastically deformed.

[0080] Vibration Damping Material

[0081] Each spacer article comprises a vibration damping material. Thevibration damping material useful in the various spacer articleembodiments comprises a viscoelastic material or combination ofdifferent viscoelastic materials. The properties described herein whichare attributable to the viscoelastic material are typically alsoattributable to the vibration damping material itself.

[0082] Typical viscoelastic materials are those having a storage modulusof at least about 1.0 psi (6.9×10³ Pascals) and a loss factor of atleast about 0.01 at the temperature and frequency of use (typicallyabout −60 to 100° C.). Advantageously and preferably, the vibrationdamping material is placed in areas of high strain energy to provideimproved damping in the desired frequency and temperature range.

[0083] A viscoelastic material is one that is viscous, and thereforecapable of dissipating energy, yet exhibits certain elastic properties,and therefore is capable of storing energy. That is, a viscoelasticmaterial is an elastomeric material typically containing long-chainmolecules that can convert mechanical energy into heat when they aredeformed. Such a material typically can be deformed (e.g., stretched) byan applied load and gradually regain its original shape or contractsometime after the load has been removed.

[0084] Typical viscoelastic materials for use in the vibration dampingmaterials of the present invention have a storage modulus, i.e., measureof the energy stored during deformation, of at least about 1.0 psi(6.9×10³ Pascals) at the frequency and temperature of operation, moretypically about 10-2000 psi (6.9×10⁴-1.4×10⁷ Pascals).

[0085] Typical viscoelastic materials for use in the vibration dampingmaterials of the present invention have a loss factor, i.e., the ratioof energy loss to energy stored, of at least about 0.15. Preferably theloss factor is at least about 0.3, more preferably at least about 0.5,and most preferably about 0.7-10 in the frequency and temperature rangewhere damping is required (typically about 1-10,000 Hz and 60 to about100° C., more typically about 50-5,000 Hz and about 0-100° C., and mosttypically about 50-1500 Hz and about 20-80° C.). This loss factor is ameasure of the material's ability to dissipate energy and depends on thefrequency and temperature experienced by the damping material. Forexample, for a crosslinked acrylic polymer at a frequency of 100 Hz, theloss factor at 68° F. (20° C.) is about 1.0, while at 158° F. (70° C.),the loss factor is about 0.7.

[0086] Preferred viscoelastic materials are those that remain functionalover a wide range of temperatures, e.g., about −40° C. to about 300° C.Most preferred viscoelastic materials are those that cover the broadesttemperature and frequency range at the desired minimum loss factor andstorage modulus to achieve acceptable damping of the spacer article andthat do not experience a significant degradation in properties due tolong times at high temperatures or short excursions beyond these hightemperature levels.

[0087] Useful viscoelastic damping materials can be isotropic as well asanisotropic materials, particularly with respect to elastic properties.As used herein, an “anisotropic material” or “nonisotropic material” isone in which the properties are dependent upon the direction ofmeasurement.

[0088] Suitable viscoelastic materials include urethane rubbers,silicone rubbers, nitrile rubbers, butyl rubbers, acrylic rubbers,natural rubbers, fluorine-based elastomers and rubbers,styrene-butadiene rubbers, synthetic rubbers, and the like. Other usefuldamping viscoelastic materials include acrylates, epoxy-acrylates,silicones, acrylate-silicone mixtures, cyanate esters, polyesters,polyurethanes, polyamides, ethylene-vinyl acetate copolymers, polyvinylbutyral, polyvinyl butyralpolyvinyl acetate copolymers, epoxy-acrylateinterpenetrating networks and the like. Specific examples of usefulmaterials are disclosed or referenced in U.S. Pat. No. 5,183,863; U.S.Pat. No. 5,262,232; and U.S. Pat. No. 5,308,887. Particularly preferredviscoelastic damping materials are those based on acrylates.

[0089] Examples of thermoplastic materials suitable for use as thevibration damping material include, but are not limited to, thoseselected from the group consisting of polyacrylates, polycarbonates,polyetherimides, polyesters, polysulfones, polystyrenes,acrylonitrile-butadiene-styrene block copolymers, polypropylenes, acetalpolymers, polyamides, polyvinyl chlorides, polyethylenes, polyurethanes,and combinations thereof.

[0090] Useful viscoelastic materials can also be crosslinkable toenhance their strength and/or temperature resistance. Such viscoelasticsare classified as thermosetting resins. When the viscoelastic materialis a thermosetting resin, then prior to the manufacture of the spacerarticle, the thermosetting resin is in a thermoplastic state. During themanufacturing process, the thermosetting resin is cured and/orcrosslinked typically to a solid state, although it could be a gel uponcuring, as long as the cured material possesses the viscoelasticproperties described above. Depending upon the particular thermosettingresin employed, the thermosetting resin can include a curing agent,e.g., catalyst, which, when exposed to an appropriate energy source(such as thermal energy), the curing agent initiates polymerization ofthe thermosetting resin.

[0091] The vibration damping material can optionally include additivessuch as fillers (e.g., talc, etc.), colorants, toughening agents, fireretardants, antioxidants, antistatic agents, and the like. The vibrationdamping material can optionally contain fibers and/or particulatesadditives that are designed to provide an increased thermal and/orelectrical conductive path through the vibration damping material. Thesematerials may also add force retention improvements to a spacer article,but are not required. Sufficient amounts of each of these materials canbe used to effect the desired result. The vibration damping material ofthe particulate/fiber containing spacer articles includes particulatesand/or fibers. The other spacer articles described herein may optionallyinclude such fibers and/or particulates in their vibration dampingmaterial.

[0092] A conductive material can be added to the vibration dampingmaterial to lower the electrical resistance of the viscoelastic layerbetween substrates and reduce the bias level to an acceptable level. Theresistance level is effectively reduced if a sufficient amount of anelectrically conductive material is added such that the resistance levelbetween substrates (such as substrate layers) of the spacer article isbelow about 200 ohms, preferably below about 100 ohms, more preferablyless than about 5 ohms, and most preferably less than 0.1 ohms.

[0093] The vibration damping material is bonded to, laminated to, orotherwise joined to, at least one substrate. This may occur due to theproperties of the vibration damping material itself or the spacerarticle may further comprise adhesive layer(s) that aid in bonding ofthe vibration damping material to the substrate.

[0094] The vibration damping material may optionally be secured into oronto the spacer article via tension, compression, mechanicalinterlocking, etc.

[0095] The vibration damping material that provides the significantportion of the damping may also include an effective amount of an epoxyresin dispersed within the damping material. The vibration dampingmaterial may include an amount of epoxy resin effective to improve themechanical integrity of the spacer article. The epoxy resin material mayhave damping properties. An example of a suitable damping materialincorporating an epoxy resin is disclosed in U.S. Pat. No. 5,262,232.Typically, the amount of epoxy resin incorporated into the vibrationdamping material would be about 0.5 to 95 weight percent, more typicallyabout 5 to about 50 weight percent, based on the total weight of thevibration damping material.

[0096] The vibration damping material used for a high modulus vibrationdamping material containing laminate spacer article requires a veryspecific range of performance to function as both a damping material andalso provide force retention in a spindle assembly. The viscoelasticmaterial, as tested in a rheometer at 1 Hertz and between 25° C. and 80°C., has a storage modulus of greater than about 200,000 Pascals, a lossmodulus of less than about 500,000 Pascals, and a loss factor of lessthan about 0.5, preferably less than about 0.4. Preferably, theviscoelastic material has a storage modulus of greater than about200,000 Pascals, a loss modulus of less than about 400,000 Pascals, anda loss factor of between about 0.05 and about 0.5, more preferablybetween about 0.10 and about 0.45 at 1 Hz and 25-80° C.

[0097] The viscoelastic material preferably has sufficient internalstrength (modulus) and chemical resistance to allow the laminate to bestamped, ground, machined, polished and cleaned to the desired designrequirements (desired flatness of the spacer article, force retention,tolerances, cleanliness needs, etc.) without delamination or negativeeffects caused by the stamping, grinding, machining, cleaning, andpolishing, or the fluids used in these processes. Preferably the spacerarticle demonstrates low outgassing (less than about 25 μg/cm² total)and low ionic levels (less than about 100 μg/cm² total).

[0098] The laminate spacer articles (plastically deformed, high modulus,particulate\fiber, two section spacer, etc.) that have a vibrationdamping material layer between substrates may allow an electrical biasto develop between rotating storage articles and other rotating storagearticles and/or read and write devices (such as magneto-resistive headsof a rigid disk drive) and/or drive covers and bases and also eithersubstrate side of the laminate spacer article themselves. The substratesof the spacers, rotating storage articles, cover, and/or spindle may notmake a good electrical connection due to tolerances and design of thespindle assembly and drive, leading to an electrical bias betweenvarious items noted. Furthermore, a typical vibration damping materialsis non-conducting and may be a good electrical insulator. The electricalbias between various items can potentially lead to a degradation of thereading and writing performance of the drive and even lost data.

[0099] Press Fit Laminate Spacer Article

[0100] A press fit laminate spacer article is most typically prepared byfirst preparing a laminate as previously described. The laminate isprepared from an upper substrate layer, a lower substrate layer, and alayer of vibration damping material comprising a viscoelastic materiallaminated between said upper and lower substrate layers.

[0101] A substrate component (typically circular, although it may beoval, rectangular, etc.) having a through hole (typically centrallylocated and circular, although it may be oval, rectangular, etc.)therein is provided. The substrate component is typically ring-shaped.The substrate component has an inner perimeter and an outer perimeter.The substrate component may optionally have an inner perimeter and outerperimeter that is notched, jagged-edged, hatched, contains protrusions,etc. The substrate component has a higher storage modulus than theviscoelastic material in the vibration damping material.

[0102] The dimensions of the substrate component should be sufficient toallow press fitting of the substrate component onto the inner perimeteror outer perimeter of the laminate. Typically the through hole in thesubstrate component has the same shape as the outer perimeter of thelaminate when the laminate fits within and is press fit into thesubstrate component. Typically the outer perimeter of the substratecomponent has the same shape as the inner perimeter of the laminate whenthe substrate component fits within the through hole of the laminate andis press fit into the laminate. The press fit clearance between thesubstrate component and the laminate is such that they may be closedupon each other and fit snugly, so as not to be easily displaced ormoved apart once assembled. Such a spacer is typically similar in shapeto that shown in FIG. 7.

[0103] Typically the thickness of the substrate component ranges fromabout 0.1 to about 10 mm, preferably about 0.5 to about 5 mm, and mostpreferably about 0.5 to about 3 mm. Typically the thickness of thesubstrate component is identical to the thickness of the laminate. Ifthe substrate component is much thinner than the laminate, the desiredforce retention might not be obtained.

[0104] Typically the substrate component width in a partialcross-section is about 1-90% of the overall width of the press fitlaminate spacer article partial cross-section, preferably from about10-70%, and more preferably about 10-50%.

[0105] Preferably with respect to the above press fit laminate spacerarticle the thickness and position of the laminate is such that thelaminate upper surface ranges from about 5 percent of the height of thesubstrate component below the upper surface of the substrate componentto about 5 percent of the height of the substrate component above thesubstrate component. Also preferably, the laminate lower surface rangesfrom about 5 percent of the height of the substrate component above thelower surface of the substrate component to about 5 percent of theheight of the substrate component below the lower surface of thesubstrate component. Even more preferably with respect to the abovepress fit laminate spacer article the thickness and position of thelaminate is such that the laminate upper surface ranges from about 2percent of the height of the substrate component below the upper surfaceof the substrate component to about 2 percent of the height of thesubstrate component above the substrate component. Also preferably, thelaminate lower surface ranges from being about 2 percent of the heightof the substrate component above the lower surface of the substratecomponent to about 2 percent of the height of the substrate componentbelow the lower surface of the substrate component.

[0106] Preferably with respect to all the spacer articles of theinvention, the spacer article has a force retention of at least about 92percent (more preferably at least about 95 percent, even more preferablyat least about 97 percent, and most preferably at least about 98.5percent) of an initial compression force of 1.4×10⁶ Pascals applied tothe spacer article for about 0.2 to about 2 seconds at about 25° C. andat about 15 minutes after application of the initial compression force.

[0107] The spacer article may optionally further comprise a secondlaminate having a through hole therein that is press fit into thesubstrate component perimeter that the first laminate component is notpress fit into.

[0108]FIG. 6 illustrates a damped press fit laminate spacer articlecomprising a laminate comprising a first circular substrate layer 72having a central through hole therein, a second circular substrate layer76 having a central through hole therein, and a circular layer ofvibration damping material 74 having a central through hole therein andpositioned therebetween. The laminate is press fit into a ring-shapedsubstrate component 78. The spacer article encompasses a through hole71.

[0109] Nested Substrate Spacer Article

[0110] A nested substrate spacer article comprising a vibration dampingmaterial component positioned between a first substrate and a secondsubstrate is most typically prepared as follows:

[0111] The first substrate may have a variety of shapes. It may becircular, oval, rectangular, etc. The outer perimeter of the firstsubstrate may optionally be notched, jagged-edged, hatched, containprotrusions, etc. Typically the first substrate, as well as the othersubstrates, are ring-shaped. In a preferred embodiment of the nestedsubstrate spacer article the first substrate is substantiallyring-shaped, the second substrate is substantially ring-shaped, and thevibration damping material is substantially ring-shaped.

[0112] The first substrate has a through hole therein. Typically thethrough hole is circular in shape, although it may be oval, rectangular,etc. The area of the substrate defining the through hole may optionallybe notched, jagged-edged, hatched, contain protrusions, etc. Typicallythe through hole is centrally located in the first substrate.

[0113] The first substrate has a storage modulus greater than that ofthe viscoelastic material in the vibration damping material. The firstsubstrate typically has a diameter or length of about 1 mm to about 300mm, preferably about 5 mm to about 100 mm, and most preferably about 10to about 70 mm; a thickness of about 0.01 mm to about 25 mm, preferablyabout 0.05 mm to about 10 mm, and most preferably about 0.5 mm to about5 mm; and a through hole diameter of about 0.9 mm to about 299.9 mm,preferably about 4.9 mm to about 99.9 mm, and most preferably about 9.9mm to 69.9 mm.

[0114] A smaller diameter second substrate (typically circular in shape,although it may be oval, rectangular, etc.) is provided. The secondsubstrate has a through hole therein. Typically the through hole iscircular in shape, although it may be oval, rectangular, etc. The areadefining the through hole may, optionally, be notched, jagged-edged,hatched, contain protrusions, etc. Typically the through hole iscentrally located in the second substrate. The second substrate ispositioned within the through hole of the first substrate. The outerperimeter of the second substrate may optionally be notched,jagged-edged, hatched, contain protrusions, etc.

[0115] The second substrate has a storage modulus greater than that ofthe viscoelastic material in the vibration damping material. The secondsubstrate typically has a length or diameter of about 1 mm to about 300mm, preferably about 5 mm to about 100 mm, and most preferably about 10to about 70 mm; a thickness of about 0.01 to about 25 mm, preferablyabout 0.5 mm to about 10 mm, and most preferably about 1 mm to about 5mm; and a through hole diameter of about 9.9 mm to about 299.9 mm,preferably about 4.9 mm to about 99.9 mm, and most preferably about 9.9mm to 69.9 mm. Typically the thickness ratio of the first and secondsubstrates ranges from about 1:1 to 1:20, preferably about 1:1 to about1:5, even more preferably about 1:1 to about 1:1.5, and most preferablyabout 1:1.

[0116] A vibration damping material component (typically circular,although it may be oval, rectangular, etc.) comprising a viscoelasticmaterial is provided between the two substrates, filling at least aportion of the gap between the two higher modulus substrates andcontacting both substrates. The outer and/or inner perimeter of thevibration damping material component may optionally be notched,jagged-edged, hatched, contain protrusions, etc.

[0117] Vibration damping material is positioned within the through holeof the first substrate between the first substrate and the secondsubstrate, such that it bonds the first substrate to the secondsubstrate either mechanically and/or adhesively. The substrates arepreferably off-set as defined previously herein.

[0118] The vibration damping material component typically has a partialcross-sectional thickness of about 0.001 mm to about 10 mm, preferablyabout 0.01 mm to about 5 mm, and most preferably about 0.025 mm to about3 mm.

[0119] The vibration damping material component(s) may be continuous ordiscontinuous. A discontinuous component may be separated by space(s)and/or a nondamping material. A continuous component may comprise thesame damping material or different damping materials adjacent to eachother, thereby forming a continuous component.

[0120] Optionally, more than one vibration damping material componentcan be positioned between the first and second substrate rings. Thesubstrates themselves may be continuous or discontinuous, with openings,slits, slots, protrusions, embossing features, coining features, etc.therein. The substrates, however, are typically continuous.

[0121] The spacer article may optionally further comprise additionalsubstrate(s) separated by additional vibration damping material layers.For example, the spacer article may comprise an outer, middle, and innersubstrate component that are joined by two vibration damping materialcomponents.

[0122] In a preferred embodiment of the nested substrate spacer articlethe height of the first substrate is within a range of about 95 percentof the height of the second substrate to about 105 percent of the heightof the second substrate. In an even more preferred embodiment of thespacer article the first substrate and second substrate are about thesame height. In a preferred embodiment of the nested substrate spacerarticle, the vibration damping material component is at least about 10percent of the height of the first substrate beneath the upper surfaceof the first substrate and at least about 10 percent of the height ofthe first substrate above the lower surface of the first substrate; andwherein the vibration damping material component is at least about 10percent of the height of the second substrate beneath the upper surfaceof the second substrate and at least about 10 percent of the height ofthe second substrate above the lower surface of the second substrate.

[0123] In an even more preferred embodiment of the nested substratespacer article the vibration damping material component is at leastabout 15 percent of the height of the first substrate beneath the uppersurface of the first substrate and at least about 15 percent of theheight of the first substrate above the lower surface of the firstsubstrate; and wherein the vibration damping material component is atleast about 15 percent of the height of the second substrate beneath theupper surface of the second substrate and at least about 15 percent ofthe height of the second substrate above the lower surface of the secondsubstrate.

[0124] In a preferred embodiment of the nested substrate spacer articlethe first substrate, vibration damping material component, and secondsubstrate are positioned such that the first substrate and secondsubstrate are offset from each other. More preferably the upper surfaceof the first substrate and the upper surface of the second substrate areoffset from each other by about 0.025 to about 0.5 mm and wherein thelower surface of the first substrate and the lower surface of the secondsubstrate are offset from each other by about 0.025 to about 0.5 mm.Most preferably the upper surface of the first substrate and the uppersurface of the second substrate are offset from each other by about0.025 to about 0.2 mm and wherein the lower surface of the firstsubstrate and the lower surface of the second substrate are offset fromeach other by about 0.025 to about 0.2 mm.

[0125]FIG. 33 illustrates a damped, nested substrate spacer articleuseful according to the present invention comprising a first substratering 1032 having an upper surface, a lower surface, an inner side and anouter side, wherein the inner side has a groove therein. The grooveextends around the entire inner perimeter of the first substrate ring1032. The first substrate ring 1032, which has a central through holetherein, is made, for example, of metal.

[0126] A second substrate ring 1034 has an upper surface, a lowersurface, an inner side, and an outer side, wherein the inner side has agroove therein. The groove extends around the entire outer perimeter ofthe second substrate ring 1034. The second substrate ring 1034, which ismade, for example of metal, has a central through hole therein.

[0127] A ring 1036 of vibration damping material is positioned within acavity defined by the grooves. The spacer article encompasses a throughhole 1038. Typically the height of each substrate ring (1032 and 1034)is substantially the same, more typically, the same.

[0128]FIG. 34 illustrates a damped nested substrate spacer articleuseful according to the present invention comprising a first substratering 1040 having an upper surface, a lower surface, an inner side, andan outer side, wherein the inner side has a groove therein which extendscompletely around the entire inner perimeter of the first substrate ring1040. The first substrate ring 1040, which has a central through holetherein, is made, for example of metal.

[0129] A second substrate ring 1048 having an upper surface, a lowersurface, an inner side having a groove therein that extends completelyaround the inner perimeter of the second substrate ring 1048, and anouter side having a groove therein that extends around the entire outerperimeter of the second substrate ring 1048 is positioned within thethrough hole of the first substrate ring 1040. The second substrate ring1048 has a central through hole therein and is made, for example, ofmetal.

[0130] A third substrate ring 1042 having an upper surface, a lowersurface, an inner side, and an outer side having a groove therein thatextends completely around the outer side is positioned within thethrough hole of the second substrate ring 1048.

[0131] A ring 1044 of vibration damping material is positioned withinthe grooves of the first 1040 and second 1048 substrate rings. A ring ofvibration damping material 1046 is also positioned within the grooves ofthe second 1048 and third 1042 substrate rings.

[0132] In a preferred embodiment of the spacer article, at least about25 percent of the surface area of the vibration damping material 1044,1046 is in contact with the grooves. In an even more preferredembodiment of the spacer article, at least about 50 percent of thesurface area of the vibration damping material 1044, 1046 is in contactwith the grooves. In a most preferred embodiment of the spacer article,at least about 70 percent of the surface area of the vibration dampingmaterial 1044, 1046 is in contact with the grooves. In a most preferredembodiment of the spacer article, the first substrate ring 1040 andsecond substrate ring 1048 are within at least about 0.254 mm of eachother and at least about 85% of the surface area of the vibrationdamping material 1044 fits entirely within a cavity defined by thegroove in the first substrate ring 1040 and the groove in the secondsubstrate ring 1048.

[0133] The spacer article encompasses a through hole 1050. Typically theheight of each substrate ring (1040, 1048, and 1042) is substantiallythe same, more typically, the same. It is possible for this spacerarticle to comprise additional substrates and vibration damping materialas discussed with respect to previous embodiments.

[0134] Welded Spacer Article

[0135] A welded spacer article of the present invention is mosttypically prepared by first preparing a laminate from an upper substratelayer, a lower substrate layer, and a layer of vibration dampingmaterial comprising a viscoelastic material positioned between saidupper and lower substrate layers.

[0136] The laminate can be spot welded, for example with a welding gun,such that the first substrate layer is welded to the second substratelayer. The outer periphery of the laminate can be welded such that thefirst substrate layer is welded to the second substrate layer.Alternatively, or in addition, the area of the spacer article thatdefines the through hole (the inner periphery of the laminate) maycontain welds such that the first substrate is welded to the secondsubstrate.

[0137] The number of welds can vary. One long weld, for example, may beemployed which encompasses a perimeter (inner or outer) of the article.More typically, several welds (2 to 8, for example, more typically 4 to8) that are smaller in size are employed.

[0138] A single weld typically comprises about 0.5 to about 100 percent,preferably about 0.5 to about 50 percent, and most preferably about 0.5to about 25 percent of the length of the laminate perimeter on which theweld is present. Shorter welds are preferred due to ease ofmanufacturing.

[0139] Preferably the welds are symmetrically positioned and arepositioned about the inner, outer, or both the inner and outerperimeters of the spacer article. Welds can potentially be made in areasbetween the inner and outer perimeter of the spacer, preferably withinan area that is about 25 percent of the partial cross-sectional width ofthe spacer article from an inner and/or outer perimeter of the spacerarticle.

[0140]FIG. 3 illustrates a cross-sectional view of a welded, ring-shapedspacer article of the present invention. The ring-shaped upper substratelayer is identified as 22 and the lower ring-shaped substrate layer isidentified as 26. The ring-shaped vibration damping material layerpositioned therebetween is identified as 24. The first substrate layer22 is welded to the second substrate layer 26 via welds 27. The spacerarticle encompasses a through hole 21.

[0141] Particulate/fiber Containing Spacer Article

[0142] A particulate/fiber containing spacer article of the invention ismost typically prepared by preparing a laminate from an upper substratelayer, a lower substrate layer, and a layer of vibration dampingmaterial comprising a viscoelastic material positioned between saidupper and lower substrate layers. The layer of vibration dampingmaterial further comprises an additive selected from the groupconsisting of fibers, particulate, and mixtures thereof. The totalamount of additive is about 1 to about 95 weight % based upon the totalweight of the vibration damping material. The particulate size rangesfrom about 0.05% to about 125% of the average thickness of the vibrationdamping material layer in which the particulate is present. The fiberdiameter ranges from about 0.05% to about 125% of the average thicknessof the vibration damping layer in which the fiber is present. The loadbearing capacity of the additive is at least about 100 psi (0.69 MPa).

[0143] An example of such a spacer article is that shown in FIGS. 1 and2. FIG. 1 illustrates a top view of a spacer article of the presentinvention. The upper circular substrate layer having a central throughhole 3 therein is identified as 2. FIG. 2 illustrates a cross-sectionalview of the particulate containing spacer article of FIG. 1. The uppersubstrate layer is identified as 2 and the lower substrate layer isidentified as 6. The vibration damping material layer is identified as 4and the particulate present therein is identified as 8. The spacerarticle encompasses a through hole 3.

[0144] Useful fibrous material can be, for example, in the form offibrous strands or in the form of a fiber mat or web, although fibrousstrands are preferred. The fibrous strands can be in the form ofthreads, cords, yarns, filaments, etc., as long as the viscoelasticmaterial can wet the surface of the material. They can be dispersedrandomly or uniformly in a specified order.

[0145] Preferably, the fibrous strands, i.e., fibers or fine threadlikepieces, have an aspect ratio of at least about 2:1, and more preferablyan aspect ratio within a range of about 2:1 to about 10:1. The aspectratio of a fiber is the ratio of the longer dimension of the fiber tothe shorter dimension.

[0146] Examples of useful fibrous materials include, but are not limitedto, nonmetallic fibrous materials, such as fiberglass, glass, carbon,minerals, synthetic or natural heat resistant organic materials, ceramicmaterials, and the like and metallic fibrous materials, such as steel,stainless steel, copper, aluminum, gold, silver, lead, titanium, andtheir alloys and the like. Generally, high Young's modulus fibrousmaterials, i.e., those having a modulus of at least about 100,000 psi(6.9×10⁸ Pascals), are preferred.

[0147] Useful natural organic fibrous materials include, but are notlimited to, those selected from the group consisting of wool, silk,cotton, and cellulose. Examples of useful synthetic organic fibrousmaterials include, but are not limited to, those selected from the groupconsisting of polyvinyl alcohol, nylon, polyester, rayon, polyamide,acrylic, polyolefin, aramid, and phenol. The preferred organic fibrousmaterial for applications of the present invention is aramid fibrousmaterial. Such materials are commercially available from Dupont Co.,Wilmington, Del. under the trade names “Kevlar” and “Nomex.”

[0148] Generally, any ceramic fibrous material is useful in applicationsof the present invention. An example of a ceramic fibrous materialsuitable for the present invention is available under the tradedesignation, NEXTEL, which is commercially available from MinnesotaMining and Manufacturing Co.; St. Paul, Minn. Examples of useful,commercially available, glass fibrous materials are those available fromPPG Industries, Inc.; Pittsburgh, Pa., under the product name E-glassbobbin yarn; Owens Coming; Toledo, Ohio, under the product name“Fiberglass” continuous filament yam; and Manville Corporation; Toledo,Ohio, under the product name “Star Rov 502” fiberglass roving.

[0149] Advantages can be obtained through use of fibrous materials of alength as short as about 100 micrometers. The fibers are not limited inlength, but much longer fibers may provide insufficient fiber interfaceand, therefore, decreased shearing surfaces between fibers. The fiberthickness or diameter for typical fibrous material ranges from at leastabout 5 micrometers. The thinner the fiber, the higher the surface areaof the fibrous material for a given amount of fiber loading. Thus,preferred fibrous materials are very thin. The thickness of the fiber isalso dependent upon the desired thickness of the overall dampingmaterial layer that will be used in the article. Thus, many commonfibers may not be suitable if the overall damping material thickness isrelatively thin (e.g., 4-10 micrometers).

[0150] Particulate material(s) useful in a spacer article can be in theform of bubbles or beads, flakes, powders, etc., as long as theviscoelastic can wet the surface of the material. Preferably, theparticulate material is on the size order of about 0.1 to about 5micrometers and more preferably about 0.1 to about 2 micrometers.Examples of useful particulate materials in applications of the presentinvention include metal; coated or uncoated glass and ceramic bubbles orbeads; powders, such as silica, aluminum oxide powder and aluminumnitride power; cured epoxy nodules; and the like.

[0151] Fibers and/or particulates of the right composition, size, andloading can provide the desired force retention in the spacer article.The other spacer articles described herein have their force retentionincreased by other means, although the use of such fibers and/orparticulate would not hinder their force retention and could potentiallyimprove it. The fibers and/or particulates may provide a high modulusmechanical force connection through the damping material and to thesubstrate layers, in effect, bypassing or bridging the damping materialand creating a mechanical connection that can support the attachmentdevice's force with stress relaxation less than that of the dampingmaterial. When a force is applied, the force between substrate layerscan pass through the particulates and/or fibers that connect bothsubstrate surfaces to provide reduced damping viscoelastic stressrelaxation. The fibers and/or particulate can be used in an amount tooptimize force retention.

[0152] The total amount of such particles and/or fibers included in thevibration damping material typically ranges from about 1 to about 95%,preferably about 20 to about 90%, and most preferably about 50 to about90%, based on the total weight of the vibration damping material. Thefiber diameters for fibers for such a purpose typically range from about0.05 to about 125%, preferably about 10 to about 100%, and mostpreferably about 50 to about 100%, based on the average thickness of thevibration damping layer in which the fibers are contained. The particlesize for particles for such purposes typically ranges from about 0.05 toabout 125%, preferably about 10 to about 100%, and most preferably about50 to about 100%, based on average thickness of the vibration dampinglayer in which the particles are contained.

[0153] The fibers and/or particulates will provide a high modulusmechanical force connection through the damping material and between thesubstrate layers, in effect, completely or partially bypassing orbridging the damping material and creating a mechanical connection thatcan support the attachment device's force, and/or stress, and/orpressure, with stress relaxation less than that of the vibration dampingmaterial. When a fastener device is applied, the force between substratelayers can pass through the particulates and/or fibers that connect bothsubstrate surfaces to provide reduced stress relaxation as the dampingmaterial is bypassed. The fibers and/or particulates can be used in anamount to optimize fastener device force retention. Depending on sizeand loading used, the damped spacer article's effectiveness as a dampingsystem may be reduced somewhat. The useful modulus of the fibers andparticulates is greater than about 690,000 Pascals, preferably greaterthan about 6,900,000 Pascals, and most preferably greater than about70,000,000 Pascals.

[0154] Back-to-Back Spacer Article

[0155] A back-to-back spacer article of the invention can be prepared byproviding two spacer sections and positioning them back-to-back (i.e.,second surface of one base to the second surface of the other base).Optionally, the bases can interlock. An advantage of such a back-to-backspacer article is the ability to provide a spacer article in whichdamping material is in contact with rotatable storage articles bothabove and below the spacer article, but allowing the ability to removeone rotatable storage article that is in contact with the vibrationdamping material of a spacer section without removing the other spacersection of the spacer article. The back-to-back spacer embodiment allowsthe disk drive assembly to be disassembled easily so that replacementcomponents can be added and re-assembled. Since the rotatable storagearticle can become bonded to the vibration damping material, if thisspacer article was not designed to separate into two pieces one couldpotentially end up with two rotatable storage articles bonded togetherwith one spacer article, which could make rework difficult.

[0156] This back-to-back design can also provide improved thermal shiftand balancing of components in the disk drive assembly, as eachrotatable storage article/spacer assembly is allowed to float somewhatbetween back-to-back spacers. This allows balancing of the disk driveassembly more easily during assembly. Higher RPM drives (greater than7000 RPMs) need a well balanced spindle assembly to ensure highreliability and good drive read and writing performance. Thermal shiftbetween components can also be enhanced as two disks are not directlyconnected via a solid spacer, thus allowing thermal shifting to occurmore easily and with less impact on other components.

[0157] The present invention also provides for a back-to-back spacerarticle wherein for each spacer section the base is substantially in theshape of a ring, the ring having an inner edge and an outer edge, andwherein the substrate has two sides, wherein one side is in the form ofa ring and is joined to the first surface of the base at about the inneredge of the base and the second side is in the form of a ring and isjoined to the first surface of the base at about the outer edge of thering in order to form a channel and the vibration damping material is atleast partially contained within the channel.

[0158] Preferably each substrate section of a back-to-back spacerarticle is substantially in the shape of a ring. Preferably the secondsurfaces of the bases of both spacer sections are interlocking.

[0159] Each spacer section comprises a substrate and vibration dampingmaterial, wherein the substrate comprises a base having a first surfaceand a second surface and at least one side joined to the first surfaceof the base. When two or more sides are joined to the first surface ofthe base they may be joined in a manner as to form a channel in whichthe vibration damping material can be situated.

[0160] Each substrate can be of a one-piece construction ormultiple-piece (typically two-piece if multiple-piece) construction. Aone-piece construction may have a partial cross-sectional shape of anangular sideways C, L or E, for example. A multiple-piece construction(such as a two-piece construction) may have overlapping, adjoining,interlocking, connecting, slotted, screw-shaped, angled, flat-backed,etc. pieces that together form the substrate. An adhesive composition,adhesive tape, friction, a mechanical locking mechanism or other methodof attachment may be used, if necessary, in order to hold the separatepieces of a multiple-piece construction in position to form thesubstrate.

[0161] Vibration damping material is bonded to the first surface of thesubstrate base. Each spacer section itself, as well as the resultantspacer article, encompasses a through hole, most typically a circular,centrally positioned through hole.

[0162] In a preferred embodiment, the vibration damping material extendsbeyond the highest substrate side. The vibration damping material ispreferably extended in this manner to ensure the greatest likelihood ofpartial or full contact of the exposed vibration damping material withthe rotatable storage article in contact with the spacer article as partof a disk drive assembly. The exposed vibration damping material servesto damp the rotatable storage article it is in contact with. However, itis not absolutely necessary that the vibration damping material extendbeyond the highest side of a substrate since, due to the vibration ofthe rotatable storage article adjacent to the spacer article in a diskdrive assembly, the rotatable storage article may still be able tocontact the vibration damping material.

[0163]FIG. 24 is an embodiment of the back-to-back spacer article of theinvention. One spacer section comprises a substrate 510 and a vibrationdamping material 578 comprising a viscoelastic material. The substrate510 comprises a side 512 (having a height “z”), a side 516 (having aheight “q”), and a base 514. The two sides 512 and 516 and base 514 arejoined together such that they form a channel. The substrate is aone-piece construction having an angular sideways “C” shapedconfiguration in partial cross-section. The vibration damping material578 is contained within the channel and extends above both substratesides (512 and 516). An upper surface of the vibration damping material578 present in the channel is completely exposed. The spacer articleencompasses a through hole 519.

[0164] A second spacer section comprises a substrate 520 and a vibrationdamping material 588 comprising a viscoelastic material. The substrate520 comprises a side 522 (having a height “z”), a side 526 (having aheight “q”), and a base 524. The two sides 522 and 526 and base 524 arejoined together such that they form a channel. The substrate is aone-piece construction having an angular sideways “C” shapedconfiguration in partial cross-section. The vibration damping material588 is contained within the channel and extends beyond both substratesides (522 and 526). An upper surface of the vibration damping material588 present in the channel is completely exposed.

[0165] The two spacer sections are positioned base 514 to base 524.

[0166]FIG. 25 is another embodiment of the back-to-back spacer articleof the invention. One spacer section comprises a substrate 810 and avibration damping material 886 comprising a viscoelastic material. Thesubstrate 810 comprises one side 816 (having a height “a”) and a base880. The side 816 and the base 880 are joined together. The substrate810 is a one-piece construction having a modified angular sideways “L”shaped configuration in partial cross-section. The vibration dampingmaterial 886 is contained within the channel and is bonded to the firstsurface of the base 880. The vibration damping material 886 also extendsabove the substrate side 816. An upper surface of the vibration dampingmaterial 886 present in the channel is completely exposed. The spacerarticle encompasses a through hole 884.

[0167] A second spacer section comprises a substrate 820 and a vibrationdamping material 888 comprising a viscoelastic material. The substrate820 comprises one side 826 (having a height “b”) and a base 882. Theside 826 and base 882 are joined together such that they form a channel.The substrate 820 is a one-piece construction having a modified angularsideways “L” shaped configuration in partial cross-section. Thevibration damping material 888 is contained within the channel and isbonded to the first surface of the base 882 and extends beyond thesubstrate side 826. An upper surface of the vibration damping material888 present in the channel is completely exposed.

[0168] The two spacer sections are interlocking via their bases 880 and882 due to a projection 892 in base 882 and a recession 890 in base 880.

[0169]FIG. 26 is another embodiment of the back-to-back spacer articleof the invention. One spacer section comprises a substrate 958 and avibration damping material 980 comprising a viscoelastic material. Thesubstrate 958 comprises a side 961 (having a height “e”), a side 965(having a height “f”), and a base 960. The two sides 961, 965 and base960 are joined together such that they form a channel. The substrate 958is a one piece construction having a modified angular sideways “C”shaped configuration in partial cross-section. The vibration dampingmaterial 980 is contained within the channel and is bonded to the firstsurface of the base 960 and extends above both substrate sides (961 and965). An upper surface of the vibration damping material 980 present inthe channel is completely exposed. The spacer article encompasses athrough hole 968.

[0170] A second spacer section comprises a substrate 959 and a vibrationdamping material 982 comprising a viscoelastic material. The substrate959 comprises a side 963 (having a height “g”), a side 967 (having aheight “h”), and a base 962. The two sides 963, 967 and base 962 arejoined together such that they form a channel. The substrate 959 is aone-piece construction having a modified sideways angular “C” shapedconfiguration in partial cross-section. The substrate 959 has a higherstorage modulus than the viscoelastic material in the vibration dampingmaterial 982. The vibration damping material 982 is contained within thechannel and extends beyond both substrate sides 963 and 967. An uppersurface of the vibration damping material 982 present in the channel iscompletely exposed.

[0171] The two spacer sections are interlocking via their bases due to aprojection 966 in base 962 and a recession 964 in base 960.

[0172] The vibration damping material may optionally have a constraininglayer attached to the surface thereof. This constraining layer couldpotentially contact the rotatable storage article on a spindle of a diskdrive assembly and could, thus, reduce the possibility of vibrationdamping material bonding to the rotatable storage article. Thisconstraining layer could also potentially improve the vibration dampingperformance of the spacer article. The vibration damping material andoptional constraining layer may each optionally be segmented and mayeach optionally comprise more than one layer.

[0173] The vibration damping material width as compared to the width ofthe spacer article is typically from about 1-90% of the width of thespacer in a partial cross-sectional cut, preferably from about 10-90%,and most preferably from about 25-90%.

[0174] The width of each of the sides of the spacer is typically fromabout 1-60% of the width of the spacer in a partial cross-section view,preferably from about 5-40%, and most preferably about 5%-25%.

[0175] The vibration damping material is typically positioned on thebase such that it is positioned away from the sides by at least about0.2% of the base width in a partial cross-sectional view of the basewidth away, preferably at least about 2% of the base width away, andmost preferably at least about 4% of the base width away.

[0176] The ratio of the optional constraining layer thickness to anadjacent damping material layer thickness is typically about 1:0.05 toabout 1:10, preferably about 1:0.2 to about 1:7, more preferably about1:0.2 to about 1:5, and most preferably about 1:4 to about 1:2. Thevibration damping material layer can also be provided so that it isundercut and does not extend past the edge of the constraining layer.For such an embodiment the damping material is preferably from about0-25%, more preferably about 5-25%, and most preferably 10-25% of theconstraining layer width from the edge of the constraining layer.

[0177] The vibration damping material has a height great enough suchthat it is about 90 to about 300 percent of the height of the highestsubstrate side of the spacer section, preferably 95-200%, morepreferably 100-200%, more preferably 102-150%, and most preferably102-120%.

[0178] The base of the spacer may optionally have cut-outs, recesses,notches, coins, depressions, etc. that the damping material can besqueezed into once the spacer is applied onto the spindle. This designcan minimize the squeeze-out in an undesirable direction, such as outbeyond the edge of the spacer. This design may also improve the forceretention of the spacer article.

[0179] Constrained Layer Damper Spacer Articles

[0180] The present invention also provides a constrained layer damperspacer article comprising (a) a substrate, the substrate comprising (i)a base, the base having two major opposing surfaces, an upper surfaceand a lower surface, and (ii) at least one side joined to the uppersurface of the base, each side having a height; and (b) a firstconstrained layer damper attached to the upper surface of the base. Thefirst constrained layer damper has a height such that it ranges fromabout 90 to about 300 percent of the height of the side having agreatest height on the upper surface of the base. Each constrained layerdamper independently comprises: (i) a constraining layer; and (ii) alayer of vibration damping material bonded to the constraining layer.The vibration damping material comprises viscoelastic material. Thestorage modulus of the constraining layer is greater than that of theviscoelastic material in the vibration damping material. Eachconstrained layer damper is attached to the base via its vibrationdamping material layer. The spacer article has a through hole therein.

[0181] Preferably the constrained layer damper spacer further comprises:(iii) at least one side joined to the lower surface of the base, eachside having a height; and (c) a second constrained layer damper attachedto the lower surface of the base, wherein the second constrained layerdamper has a height such that it ranges from about 90 to about 300percent of the height of the side having a greatest height on the lowersurface of the base. The second constrained layer damper independentlycomprises: (i) a constraining layer; and (ii) a layer of vibrationdamping material bonded to the constraining layer. The vibration dampingmaterial comprises viscoelastic material. The storage modulus of theconstraining layer is greater than that of the viscoelastic material inthe vibration damping material. The storage modulus of the constraininglayer is greater than that of the viscoelastic material in the vibrationdamping material. Each constrained layer damper is attached to the basevia its vibration damping material layer.

[0182]FIG. 27 illustrates a constrained layer damper spacer article ofthe invention. The spacer article comprises a ring-shaped substrate 891,the substrate 891 comprising a ring-shaped base 890, the base 890 havingtwo major opposing surfaces, an upper surface 893 and a lower surface895, and a ring-shaped side 897 joined to the upper surface 893 of thebase 890, the side 987 (having a height “x”) and several constrainedlayer dampers (each having a height “y”) attached to the upper surface893 of the base 890. The constraining layers described herein typicallyhave the same properties and are made of the same materials as thepreviously described substrates.

[0183] Each constrained layer damper comprises a constraining layer 892and a layer of vibration damping material 894 bonded thereto. Eachconstrained layer damper is attached to the upper surface 893 of thebase 890 via its vibration damping material layer 894. The spacerarticle 891 has a through hole 896 therein.

[0184]FIG. 28 illustrates a constrained layer damper spacer article. Thespacer article comprises a ring-shaped substrate 909, the substrate 909comprising a ring-shaped base 911 (the base 911 having two majoropposing surfaces, an upper surface 913 and a lower surface 915) and aring-shaped side 900 joined to the upper surface 913 of the base 911,the side 900 having a height (x) and a ring-shaped constrained layerdamper having a height (y) attached to the upper surface 913 of the base909. The constrained layer damper comprises a ring-shaped constraininglayer 902 and a ring-shaped layer of vibration damping material 904bonded thereto. The constrained layer damper is attached to the uppersurface 913 of the base 909 via its vibration damping material layer904.

[0185] A side 987 is also joined to the lower surface 915 of the base909, the side 987 having a height (x). A second constrained layer damperis attached to the lower surface 915 of the base 909. The secondconstrained layer damper has a height (y). The second constrained layerdamper comprises a constraining layer 918 and a layer of vibrationdamping material 919 bonded thereto. The spacer article has a throughhole 906 therein.

[0186] The constrained layer damper width as compared to the width ofthe spacer article is typically from about 1-90% of the width of thespacer in a partial cross-section, preferably from about 10-75%, andmost preferably from about 15-65%.

[0187] The width of the side of the spacer is typically from about 1-95%of the width of the spacer in a partial cross-section, preferably fromabout 10-75%, and most preferably about 20%-75%. The width of the sidemay affect the force retention of the spacer article. The width of aside may also affect the flatness of a rotatable storage articlepositioned adjacent to the spacer on a disk drive assembly. Theconstrained layer damper is preferably positioned onto the base suchthat it is positioned away from the side and does not hang over the baseedge.

[0188] The ratio of the constraining layer thickness to an adjacentvibration damping material layer thickness is typically about 1:0.05 toabout 1:10, preferably about 1:0.2 to about 1:7, more preferably about1:0.2 to about 1:5, and most preferably 1:0.4 to about 1:2.

[0189] The vibration damping material layer can also be provided so thatit is undercut and does not extend past the edge of the constraininglayer. For such an embodiment, the damping material is preferably fromabout 0-25% of the constraining layer width from an edge of theconstraining layer, more preferably about 5-25%, and most preferably10-25% of the constraining layer width from the edge of the constraininglayer.

[0190] The constrained layer damper attached to the upper surface of thebase has a height such that it ranges from about 90 to about 300 percentof the height of the side having a greatest height on the upper surfaceof the base, preferably about 95-200%, more preferably about 100-150%and most preferably about 102-120%.

[0191] The base of the spacer may optionally lay at an angle to theside, from about 45-145 degrees, preferably from about 60-120 degrees,more preferably about 80 to 110 degrees, and most preferably about 80 toabout 100 degrees. The angle can be used to improve shearing into thedamping material.

[0192] The base of the spacer may optionally have cut-outs, recesses,notches, coins, depressions, etc. that the damping material can besqueezed into once the spacer is applied onto the spindle. This designcan minimize the squeeze-out in an undesirable direction, such as outbeyond the edge of the constraining layer, which could allow the dampingmaterial to contact the rotatable storage article, which may bedetrimental to the drive function. This design may also result in aspacer article with improved force retention.

[0193] In a preferred embodiment, the first constrained layer damper hasa height of about 0.01 to about 0.5 mm (more preferably about 0.01 toabout 0.25 mm, and most preferably about 0.2 to about 0.1 mm) greaterthan the height of the side having the greatest height on the uppersurface of the base. The second constrained layer damper has a height ofabout 0.01 to about 0.5 mm (more preferably about 0.01 to about 0.25 mm,and most preferably about 0.2 to about 0.1 mm) greater than the heightof the side having the greatest height on the lower surface of the base.

[0194] Two Section Spacer Article

[0195] The present invention also provides a two section spacer articlecomprising: (a) two substrate sections which are identified as a firstsubstrate section and a second substrate section and (b) a vibrationdamping material comprising viscoelastic material. The first substratesection has a through hole, a base and a side joined to the base thatextends above and below the base. The side has a height and an uppersurface and a lower surface. The side defines an outer perimeter of thefirst substrate section and the base defines an inner perimeter of thefirst substrate section.

[0196] The second substrate section has a through hole, a base and aside joined to the base that extends above and below the base. The sidehas a height and an upper surface and a lower surface. The base definesan outer perimeter of the substrate section and the side defines aninner perimeter of the substrate section. The second substrate sectionfits within the through hole of the first substrate section. The side ofthe first substrate section has a height that falls within a range ofabout 90 percent of the height of the side of the second substratesection to a height about 110 percent of the height of the side of thesecond substrate section.

[0197] The storage modulus of the substrate sections are greater thanthat of the viscoelastic material in the vibration damping material. Thetwo substrate sections are joined together via the vibration dampingmaterial laminated between the bases of the two substrate sections, suchthat upper surface of the side of the first substrate section is notgreater than about 10%, more preferably 5%, of the height of the side ofthe second substrate section above the upper surface of the side of thesecond substrate section nor greater than about 10%, more preferably 5%,of the height of the side of the second substrate section below theupper surface of the side of the second substrate. The substratesections are joined such that lower surface of the first substratesection is not greater than about 10%, more preferably 5%, of the heightof the side of the second substrate section above the lower surface ofthe side of the second substrate section nor greater than 10%, morepreferably 5%, of the height of the side of the second substrate belowthe lower surface of the side of the second substrate. The spacerarticle has a through hole therein.

[0198] Preferably the two section spacer article has a force retentionof at least about 92 percent of an initial compression force of 1.4×10⁶Pascals applied to the spacer article for about 0.2 to about 2 secondsat about 25° C. at about 15 minutes after the application of the initialcompression force.

[0199] Preferably, the upper surface of the side of the first substratesection is level with the upper surface of the side of the secondsubstrate section and the lower surface of the side of the firstsubstrate section is level with the lower surface of the side of thesecond substrate section. Preferably, each spacer section issubstantially ring-shaped and the spacer article is substantiallyring-shaped.

[0200] A two section spacer article is typically prepared as follows:Two substrate sections are provided. Each substrate section comprises ahorizontal base and a vertical side joined together via their horizontalbases. The horizontal base and vertical side are typically perpendicularto each other. Vibration damping material is laminated between thehorizontal bases of the two substrate sections. Each substrate sectiontypically has a sideways “T” or “L” shape in partial cross-section. Theheight of each vertical projection is substantially the same, typicallythe same. The spacer is designed such that the force applied to thespacer from above passes through the vertical sides. The spacer articleis also designed such that it encompasses a through hole.

[0201]FIG. 18 discloses one embodiment of the two section spacer articleof the invention. A laminate is prepared from a first substrate section720 (“T”-shaped) and a second substrate section 726 (“L”-shaped). Alayer of vibration damping material 732 comprising a viscoelasticmaterial is positioned between said first 720 and second 726 substratesections. The two substrate sections 720 and 726 are joined together viathe vibration damping material 732. The T-shaped substrate section 720comprises a horizontal base 724 and a vertical side 722 joined together.The L-shaped substrate section 726 comprises a horizontal base 730 and avertical side 728 joined together. The vibration damping material 732 islaminated or otherwise positioned between the horizontal bases 724 and730 of the two substrate sections 720 and 726. The height of eachvertical side 722 and 728 is substantially the same. The spacer articleencompasses a through hole 727.

[0202]FIG. 19 discloses another embodiment of the two section spacerarticle of the invention. A laminate is prepared from a first substratesection 740 and a second substrate section 746. A layer of vibrationdamping material 752 comprising a viscoelastic material is positionedbetween said first 740 and second 746 substrate sections. The twosubstrate sections 740 and 746 are joined together via the vibrationdamping material 752. L-shaped substrate section 746 comprises ahorizontal base 750 and a vertical side 748 joined together. L-shapedsubstrate section 740 comprises a horizontal base 744 and a verticalside 742 attached together. The vibration damping material 752 islaminated or otherwise positioned between the horizontal bases 744 and750 of the two substrate sections 740 and 746. The height of eachvertical projection 742 and 748 is substantially the same. The spacerarticle encompasses a through hole 727.

[0203]FIG. 21 discloses another embodiment of the two section spacerarticle of the invention. A laminate is prepared from a first substratesection 780 and a second substrate section 786. Two layers of vibrationdamping material 802 and 806 comprising a viscoelastic material arepositioned between said first 780 and second 786 sections. The twosubstrate sections 780 and 786 are joined together via the vibrationdamping material layers 802 and 806 and an internal substrate layer 804.The L-shaped substrate section 780 comprises a horizontal base 784 and avertical side 782 joined together. The other L-shaped substrate section786 comprises a horizontal base 800 and a vertical side 788 joinedtogether. The two substrate sections 780 and 786 are joined together viatheir horizontal bases 784 and 800. The vibration damping material 802and 806 is laminated or otherwise positioned between the horizontalbases 784 and 800 of the two substrate sections 780 and 786. The heightof each vertical side 782 and 788 is substantially the same. The spacerarticle encompasses a through hole 810.

[0204] U-shaped Laminate Spacer Article

[0205] A U-shaped laminate spacer article of the invention is typicallyprepared as follows: A layer of vibration damping material is laminatedbetween two substrate layers. The laminate is stamped, coined, embossed,molded or otherwise formed such that, in partial cross-section, thelaminate has a configuration which is U-shaped (either right side up,upside down or sideways). The spacer article is designed such that itcontains a through hole. The thickness of each substrate layer typicallyranges from about 0.01 mm to about 10 mm, preferably about 0.3 mm toabout 5 mm, and most preferably 0.3 mm to about 2 mm. The thickness ofthe vibration damping material typically ranges from about 0.001 mm toabout 1 mm, preferably from about 0.01 mm to about 0.5 mm, and mostpreferably about 0.015 mm to about 0.25 mm. The laminate may optionallyfurther comprise additional substrate and vibration damping materiallayers.

[0206]FIG. 20 is a cross-section of an embodiment of a U-shaped laminatespacer article of the invention. The spacer article comprises a laminatecomprising a first substrate layer 760, a second substrate layer 764,and a layer of vibration damping material 762 laminated between the twosubstrate layers 760 and 764. The laminate has a configuration which isU-shaped and sideways in partial cross-section. The spacer article,which is ring-shaped, encompasses a through hole 766.

[0207]FIG. 22 is a cross-section of another embodiment of a U-shapedlaminate spacer article of the invention. The spacer article comprises alaminate prepared from a first substrate layer 820, a second substratelayer 826, and a layer of vibration damping material 824 comprising aviscoelastic material laminated between said first 820 and second 826substrate layers. The laminate has a configuration in partialcross-section which is U-shaped and upside down. The spacer articleencompasses a through hole 828.

[0208]FIG. 23 is a cross-section of another embodiment of a U-shapedspacer article embodiment of the invention. The spacer article comprisesa laminate prepared from a first substrate layer 840, a second substratelayer 844, and a layer of vibration damping material 842 comprising aviscoelastic material laminated between said first 840 and second 844substrate layers. The layer of vibration damping material 842 islaminated between the two substrate layers 840 and 844 within thelaminate. An additional vibration damping material layer 846 ispositioned between the folded substrate layer 844. The laminate has aconfiguration which, in partial cross-section, is U-shaped and sideways.The spacer article encompasses a through hole 848.

[0209] U-shaped Spacer Article Having One Substrate Layer

[0210] The present invention also provides a U-shaped laminate spacerarticle comprising: a laminate, wherein the laminate comprises: (a) twosubstrate layers; and (b) a layer of vibration damping materialcomprising viscoelastic material. The storage modulus of each substratelayer is greater than that of the viscoelastic material in the vibrationdamping material. The layer of vibration damping material is laminatedbetween the two substrate layers within the laminate. The laminate has aconfiguration in partial cross-section which is U shaped. The spacerarticle has a through hole therein.

[0211] Preferably the spacer article has a force retention of at leastabout 92 percent of an initial compression force of 1.4×10⁶ Pascalsapplied to the spacer article for about 0.2 to about 2 seconds at about25° C. at about 15 minutes after the application of the initialcompression force.

[0212] The present invention also provides a U-shaped spacer articlehaving a substrate layer comprising: (a) a substrate, the substratehaving a through hole, the substrate having a sideways U-shape inpartial cross-section, the substrate comprising an upper base, a lowerbase, and a side joining the upper base and the lower base, and aninternal cavity; and (b) vibration damping material comprisingviscoelastic material. Preferably the substrate is substantially ringshaped and the vibration damping material is substantially ring-shaped.The storage modulus of the substrate is greater than that of theviscoelastic material in the vibration damping material. The vibrationdamping material is positioned within the cavity of the substrate suchthat it is contact with at least both the upper base and the lower baseof the substrate. The spacer article has a through hole therein.

[0213]FIG. 29 illustrates one embodiment of a U-shaped spacer articlehaving one substrate layer. The spacer article comprises a substrate951, the substrate 951 having a through hole 954, the substrate 951having a sideways U-shape in partial cross-section, the substrate 951comprising an upper base 950, a lower base 953, and a side 955 joiningthe upper base 950 and the lower base 953, and the substrate having aninternal cavity 956. A vibration damping material 952 comprisingviscoelastic material is positioned within the cavity 956 of thesubstrate 951 such that it is in contact with at least both the upperbase 950 and the lower base 953 of the substrate 951. The vibrationdamping material 952 may optionally also contact the side inside thecavity 956.

[0214]FIG. 30 illustrates another embodiment of a U-shaped spacerarticle having one substrate layer. The spacer article comprises asubstrate 981, the substrate 981 having a through hole 986, thesubstrate 981 having a sideways U-shape in partial cross-section, thesubstrate 981 comprising an upper base 980, a lower base 983, and a side985 joining the upper base 980 and the lower base 983, and the substratehaving an internal cavity 986. A vibration damping material 982comprising viscoelastic material is positioned within the cavity 986 ofthe substrate 981 such that it is in contact with at least both theupper base 980 and the lower base 983 of the substrate 981. The upperbase 980 and lower base 983 each contain notches 984 therein. Thenotches 984 are positioned such that they are on the edge of the upperbase 980 and lower base 983, which edges are not joined to the side 985.These notches 984 serve to increase the strain energy directed into thevibration damping material, which provides improved damping performance.

[0215]FIG. 31 illustrates another embodiment of a U-shaped spacerarticle having one substrate layer. The spacer article comprises asubstrate 991, the substrate 991 having a through hole 998, thesubstrate 991 having a sideways U-shape in partial cross-section, thesubstrate 991 comprising an upper base 993, a lower base 995, and a side990 joining the upper base 993 and the lower base 995, and the substrate991 having an internal cavity 997. A vibration damping material 992comprising viscoelastic material is positioned within the cavity 997 ofthe substrate 991 such that it is in contact with at least both theupper base 993 and the lower base 995 of the substrate 991. The upperbase 993 and lower base 995 each contain projections 994 on the outersurface (the surface opposite those surfaces encompassing the cavity997). The projections 994 are positioned such that they are on the edgeof the upper base 993 and lower base 995, which edges are not joined tothe side 990. These projections 994 serve to increase the strain energydirected into the vibration damping material, which provides improveddamping performance.

[0216] The spacer article typically has an upper base and lower basethat are of the same thickness, but they can differ. Typically, theupper and lower base each have a thickness that is from about 0.05% toabout 40% of the spacer's overall thickness, preferably about 1% toabout 30%, and most preferably about 1 to about 20%.

[0217] The side of the spacer article typically has a width of about1-90% of the overall spacer's width when viewed in partialcross-section, preferably about 5-50%, and most preferably about 5-30%.

[0218] The vibration damping material portion (which may, for example,be round, square, rectangular or other geometric cross-section shape,and may be either continuous or discontinuous) contacts both bases.Typically, the vibration damping material is in the shape of a ring. Thedamping material is typically under some degree of compression and/orelongation and/or stretching which decreases its height by typicallyabout 0.05-75% of its uncompressed/unelongated height, more typicallyabout 1-25%, even more typically about 1-10%, and most typically byabout 1-5% of its uncompressed and/or unelongated height. The vibrationdamping material in the cavity is compressed and/or elongated such thatits height within the cavity is reduced by about 0.05 to about 75% ofits initial uncompressed and/or unelongated height. The vibrationdamping material may be under tension and/or compression forces when itis fit into the cavity. The height of the vibration damping material mayalso be its partial cross-sectional thickness or width.

[0219] The vibration damping material can optionally be segmented,hatched, slotted, slit, notched, contain depressions, lips, edges,bevels, etc. to aid in the compression of the damping material forinitial fitting into the spacer and also to increase its dampingproperties.

[0220] The vibration damping material may optionally be poured, molded,injected or dispensed into the cavity and optionally cured in place.Alternatively, the vibration damping material can optionally bepre-molded and mechanically fit into place within the cavity. The cavitycan optionally have one or more damping materials placed into it.

[0221] The thinner the base layer, the more easily the base can bedeflected by the rotatable storage article's vibration modes, allowingthe vibration damping material under compression to be sheared and/orcompression/tension deflected by the base layer movement and providedamping to reduce the rotatable storage article's vibrations.

[0222] The damping material is typically positioned such that less thanabout 50% of the damping material extends past the edge of the base orcavity, preferably less than about 10%, more preferably 0% and mostpreferably the damping material is from 120% of the base width whenviewed in partial cross-section inside the cavity and away from the edgeof the base. It is preferable that the damping material also contact theinside edge of the side within the cavity.

[0223] The spacer article prior to placement onto a spindle assembly mayhave an outward bow to the base(s) due to the vibration damping materialdesign selected. The bow of the base may be overcome by the force usedto hold the rotatable storage article and spacer article on the spindle.If present, the bow is typically less than about 20% of the spacerthickness, preferably less than about 10%, and most preferably less thanabout 5%.

[0224] High Modulus Vibration Damping Material Containing LaminateSpacer Article

[0225] In another embodiment, the disk drive assembly of the inventionutilizes a spacer article that contains a high modulus vibration dampingmaterial that is capable of providing the desired force retention.

[0226] The present invention also provides disk drive assemblycomprising: (a) a disk drive, the disk drive having a spindle; (b) arotatable storage article positioned such that the spindle extendsthrough a through hole in the rotatable storage article; (c) a highmodulus vibration damping material containing laminate spacer articleand (d) a means for securing the rotatable storage article and spacerarticle onto the spindle. The spacer article is positioned such that thespindle extends through a through hole in the spacer article. The spacerarticle is positioned adjacent to and in contact with the rotatablestorage article. The spacer article comprises: a laminate having athrough hole, the laminate comprising: (i) an upper substrate layer anda lower substrate layer; and (ii) a layer of vibration damping materialcomprising a viscoelastic material positioned between said upper andlower substrate layers. The viscoelastic material has a loss modulus ofless than about 500,000 Pascals, a storage modulus greater than about200,000 Pascals, and a loss factor of less than about 0.5 when measuredat 1 Hertz and between 25 and 80° C. The storage modulus of eachsubstrate layer is greater than that of the viscoelastic material in thevibration damping material layer. The spacer article has a forceretention of at least about 92 percent of an initial compression forceof 1.4×10⁶ Pascals applied to the spacer article for about 0.2 to about2 seconds at about 25° C. at about 15 minutes after the application ofthe initial compression force.

[0227]FIG. 35 illustrates such a spacer article. The spacer article 89comprises a laminate having a through hole 93, the laminate comprisingan upper substrate layer 90, a lower substrate layer 91, and a layer ofvibration damping material 92 comprising a viscoelastic materialpositioned between said upper 90 and lower 91 substrate layers.

[0228] The viscoelastic material has a loss modulus of less than about500,000 Pascals, a storage modulus of greater than about 200,000Pascals, and a loss factor of less than about 0.5 when measured at 1Hertz and between 25-80° C. The storage modulus of each substrate layer90 and 91 is greater than that of the viscoelastic material in thevibration damping material layer 92. The preferred viscoelastic materialhas a loss modulus of less than about 400,000 Pascals, a storage modulusof greater than about 250,000 Pascals, and a loss factor of betweenabout 0.05 and about 0.45, more preferably a loss factor between about0.1 and about 0.4, when measured at 1 Hertz and between 25-80° C. Theproperties of the viscoelastic material not only contribute to the forceretention properties of the spacer article but can also affect themachining process. The aforementioned viscoelastic properties preferablyprovide sufficient internal strength to result in good machining,stamping, grinding, sanding, deburring, etc., characteristics. That is,these processes are more likely to occur without delamination of thelaminate.

[0229] The spacer article design provides for a force retention of thespacer article of at least about 92%, preferably at least about 95% andmost preferably about 97% of an initial force of 1.4×10⁶ Pascals that isapplied to the spacer article for a duration of about 0.2 to about 2seconds at 25° C. for about 15 minutes after the application of theinitial force.

[0230] Plastically Deformed Spacer Article

[0231] The present invention provides in one embodiment a dampedlaminate spacer article having at least one intended force applicationarea on the laminate spacer article wherein the vibration dampingmaterial layer is less massive or nonexistent and one or more substratelayers are plastically deformed. Since the damping material is typicallyreduced or nonexistent only in the intended force application area(s),this allows a laminate spacer article to be optimally designed for theapplication in terms of vibration damping material thickness for controlof resonant vibration or shock and also noise generation ortransmission, plus for forming requirements the laminate spacer articlemay need to meet. The force application area(s) provide improved forceretention upon application of a force from a rotatable storage article,another spacer article and/or an attachment device such as a clamp.Since the vibration damping layer is less massive or nonexistent only ina very small area, this does not significantly affect the overall designor effectiveness of the vibration damping spacer article.

[0232] A plastically deformed spacer article of the invention is mosttypically prepared as follows:

[0233] A laminate is prepared from an upper substrate layer, a lowersubstrate layer and a layer of vibration damping material comprising aviscoelastic material positioned between said upper and lower substratelayers. A deformation area is provided in the laminate, wherein adeformation area is an area of the spacer article wherein at least onesubstrate layer is plastically deformed such that at least two substratelayers are touching or positioned closer to each other than in an areaof the spacer article in which none of the substrates are plasticallydeformed.

[0234] Preferably at least one substrate layer of the plasticallydeformed spacer article is selected from the group consisting of thefirst and second substrate layers has at least one of the followingfeatures selected from the group consisting of protrusions, recessions,bevels, indentations, ledges, coins, ridges and notches in at least onedeformation area. Preferably at least one substrate layer has a variablethickness in a deformation area.

[0235] The deformation area is such that within at least a 0.5% area ofthe deformation area, the vibration damping material is non-existent or,if present, has a mass that is 90 percent or less, more typically 50percent of less, and most typically about 25 percent or less than theaverage mass of the vibration damping material layer of an equal area inan area of the spacer article which is not in a deformation area. Thedeformation area has a surface area that is typically about 0.05 toabout 90% of the surface area of the spacer article, preferably about0.05% to about 50%, more preferably about 0.05% to about 30%, and mostpreferably about 0.05% to about 15%.

[0236] The deformation can be provided, as one example, by using anappropriate punch to deform the laminate by placing the laminate in astamping press, for example, and impinging the punch directly above thethrough hole area of the laminate spacer article. The punch may, forexample, deform the upper top surface of the laminate around the throughhole such that the top surface of the upper substrate is plasticallydeformed such that it is angled in a direction towards the lowersubstrate. The deformation in the top substrate, thus, may be of a ringshape. An example of such a deformed spacer article is that shown inFIG. 4. As another example, the outer surface of the upper substrate maybe plastically deformed such that it is angled towards the lowersubstrate. Alternatively, both the inner surface and the outer surfaceof the upper substrate may be deformed towards the lower substrate.Other patterns of deformation are possible in both the upper and/orlower substrate as long as the appropriate force retention is obtained.

[0237] Typically, an amount of the damping material is present such thatthe damping characteristics of the spacer article are improved over anon-laminate or monolithic spacer article as used in the sameapplication, for example, as a disk spacer in a hard disk drive.Preferably, a sufficient amount of the vibration damping material isused such that the damping is improved by at least about 10% in at leastone vibrational mode.

[0238] This laminate spacer article is then stamped out and stamped withvarious tools and dies that provide the needed part definition(embossing, blanking, forming, coining, sanding, deburring, grinding,etc.) The final laminated spacer article during this stamping processhas holes pierced in it to provide a path for the disk drive spindle.The force application areas are further modified either before or afterpiercing with a tool punch to displace the vibration damping material,impart a deformation into the substrate layer(s) to reduce the vibrationdamping material's recovery and minimize residual spring effect betweenthe substrate layers, to provide a deformed laminate spacer article withimproved force and/or torque and/or pressure retention and preferablyhigh damping performance in a disk drive assembly as compared to anidentical non-laminate spacer article (improved damping) and also alaminate spacer article (improved force retention.) FIG. 4 illustrates across-sectional view of a ring-shaped deformed spacer article of thepresent invention. The upper substrate layer is identified as 30 and thelower substrate layer is identified as 34. The vibration dampingmaterial layer is identified as 32. A portion 35 of the upper substratelayer 30 surrounding a central hole 31 is plastically deformed such thatit is closer to lower substrate layer 34. The deformation area isidentified as 33.

[0239]FIG. 13 is a partial cross-section of another embodiment of aring-shaped deformed laminate spacer article of the invention comprisingupper substrate layer 420, lower substrate layer 422, through hole 432,vibration damping material layer 424, deformation 428 and protrusions430 and 426 of the upper substrate layer 420, and deformation area 434.

[0240]FIG. 14 is a partial cross-section of another embodiment of aring-shaped deformed laminate spacer article of the invention comprisingupper substrate layer 440, lower substrate layer 442, through hole 451,vibration damping material layer 444, deformations 446 and 450 andprotrusions 448 and 452 of the upper substrate layer 440, anddeformation areas 454 and 456.

[0241]FIG. 15 is a partial cross-section of another embodiment of aring-shaped deformed laminate spacer article of the invention comprisingupper substrate layer 460, lower substrate layer 464, through hole 468,vibration damping material layer 462, deformation 466 of the uppersubstrate layer 460, and deformation area 470.

[0242]FIG. 16 is a partial cross-section of another embodiment of aring-shaped deformed laminate spacer article of the invention comprisingupper substrate layer 474, lower substrate layer 478, through hole 482,vibration damping material layer 476, circular deformation 480 of theupper substrate layer 474, and deformation area 484.

[0243]FIG. 17 is a partial cross-section of another embodiment of aring-shaped deformed laminate spacer article of the invention comprisingupper substrate layer 490, lower substrate layer 492, through hole 504,vibration damping material layer 494, deformations 500 of the uppersubstrate layer 490, and deformation area 502.

[0244]FIG. 32 is a partial cross-section of yet another embodiment of aring-shaped deformed laminate spacer article of the invention comprisingupper substrate layer 1010, lower substrate layer 1014, inner substratelayer 1012, through hole 1018, vibration damping material layers 1020and 1022, deformations 1019 and 1021, and deformation area 1023.

[0245] Tooling and Method for the Deformed Spacer Article

[0246] The deformed damped laminate spacer article of the invention istypically made by a method wherein at least a portion of the vibrationdamping material is permanently displaced and the substrate layer(s) isplastically deformed in the intended force application area to provideimproved force retention of the attachment device as compared to asimilar laminate spacer article that does not have the damping materialpermanently displaced and the substrate layers plastically deformed (anddoes not use a fibrous, particulate or filler enhanced damping materialto bridge the damping material) in the same area. Since mostapplications require more than one spacer, typically 1-8 spacers ormore, the force loss is coupled between the spacers. Thus, a 1%improvement in force retention for a design may seem small, but in agiven application the 1% force loss improvement coupled to 8 spacers isa force retention loss not experienced of many psi, thus enabling theforce application system to retain sufficient force in an application.For example, force retention loss of a few percent in a disk driveassembly could allow a disk to shift due to a shock and cause data to belost that was written onto the disk previously.

[0247] The damping material is typically permanently displaced and thesubstrate layers are typically plastically deformed in the intendedforce application area by means of applying pressure to at least oneouter substrate layer surrounding the vibration damping material layerand forcing the vibration damping material away from the intendedfastener area. The substrate layers take on a permanent set (plasticdeformation) from the force or pressure used to displace the vibrationdamping material, thus, hindering the vibration damping material fromrecovering back into the area from which it was displaced.

[0248] If a substrate layer is not sufficiently plastically deformed, itcan recover back to a portion of its pre-deformation position. This cancreate a spacing between substrate layers and a residual spring force.When the attachment device is attached in this area, this residualspring force can reduce the force retention of the attachment device asthe initial force used to apply the attachment device is used toovercome the residual spring force in the substrate layers.

[0249] The punch tools useful according to the invention can be used toconcentrate force(s) in a desired localized area to permanently displaceat least a portion of vibration damping material in the intended forceapplication area of the damped laminate article and to plasticallydeform at least one substrate layer in such a way as to eliminate orminimize the amount of elastic recovery of the vibration dampingmaterial and also to limit the residual spring force between substratelayers.

[0250] The through hole area (and/or another area of the laminatearticle such as a central portion and/or an outer edge) can be subjectedto an applied force via a specifically designed punch tool that uses aspecific punch design to concentrate the punch force and permanentlydisplace at least a portion of the vibration damping material andplastically deform the substrate layer(s) in the intended deformationarea. Typically, the location of the through hole is such that thethrough hole is surrounded by a deformation area. The through hole mayalso be partially surrounded by a deformation area. Typically the areaof each deformation area surrounding or partially surrounding at leastone through hole is about 0.001 to about 100 times the area of eachthrough hole, preferably about 0.001 to about 1 times the area of eachthrough hole.

[0251] At least one substrate in the deformed spacer article of theinvention may have a variable thickness in a deformation area. Thespacer article of the invention may have at least one protrusion and/orindentation (such as a ledge, raised design, valley, crevice, notch,crimp, bevel, coin, ridge, etc.) in the first and/or second substratelayer (and any optional substrate layer).

[0252] The punch tool will also impart a feature or deformation into thelaminate spacer article by plastically deforming at least one substratein addition to displacing at least a portion of the vibration dampingmaterial. The outer substrates of the laminate spacer article maycontain protrusions and/or depressions such as ledges, notches, bevels,etc.

[0253] Instead of providing a laminate and then deforming the substratelayer(s), one may optionally initially provide substrate layer(s)wherein at least one layer has a deformation and provide a layer ofvibration damping material therebetween.

[0254] Design considerations of the punch tool used to make the deformedspacer article include the tool's ability to limit the amount ofslippage of the outer substrate layers (the upper and lower substratelayers) by applying frictional and/or gripping and/or holding forces tothe substrate areas and to concentrate the deformation forces of thetool to permanently displace the damping material, deform the substratelayers to minimize substrate layer residual spring force and minimizethe recovery of the damping material and feature the deformation area tominimize the surface area that will contact the attachment device andreduce dynamic friction.

[0255] Methods or materials to improve the tool's operation indisplacing the vibration damping material and plastically deforming thesubstrate(s) during the stamping operation include, but are not limitedto, the following:

[0256] a) Heating the damped laminate spacer article to lower themodulus of the vibration damping material for the deformation of thelaminate spacer article. This added heat allows the vibration dampingmaterial to be more easily displaced (less force needed to displace) asits modulus is lower. Heat applied during stamping is much moredesirable, simple and cost effective than using heat during the assemblyof the deformed laminate spacer article of the invention and a rotatablestorage article(s) with an attachment device on a disk drive. Heat canbe applied to the laminate during or before the deformation processstep. The heat can be applied using ultraviolet or infrared heatsources, steam, heated air, ovens, etc., such that the dampingmaterial's storage modulus is lowered. The damping material is usefullyreduced in modulus if the storage modulus at the deformation step isreduced by at least 10%, preferably by 25% and most preferably by atleast 50%;

[0257] b) Using vibration damping materials with little to nocrosslinking to reduce the force needed to displace the vibrationdamping material during the deformation process;

[0258] c) Making and using a damped laminate spacer article wherein thevibration damping layer initially has less mass in the area(s) to bedeformed to reduce the force needed to displace the damping material.This method, however, requires a more complex process to manufacture thelaminate spacer article; and

[0259] d) Using lubricants to reduce frictional losses in the tool as itdeforms the substrate(s). Lubricants will also increase the tool's life.

[0260] The tool used to reduce and/or eliminate the vibration dampingmaterial will also deform the substrate layer(s). The deformation ofthese layer(s) can lead to a hole size reduction as the substrate layercan be plastically deformed to narrow the hole size. (Hole size couldalso be increased). The deformation process can also lead to slightlyraised substrate surfaces or protruding edges caused by the particulartool used to displace the vibration damping material. Knowledge thatthis will occur is sufficient to design the completed damped laminatespacer article such that desired design criteria can be met, such as fora specific finished hole diameter. For example, the initial holediameter can be selected to be larger than the desired final holediameter such that when the deformation process occurs, the substratelayers are deformed such that the hole diameter will decrease due to theplastic deformation of the substrate layers to yield a final desiredarticle having the desired hole diameter.

[0261] The method used according to the invention can be designed tominimize the displacement of the substrate layer(s) in areas that arenot desired if the deformation of the substrate layer(s) is problematic.Options to accomplish this include, but are not limited to, the use ofsecondary tools after the deformation process that reform the substratelayers to a more desirable configuration while having a minimal effecton the force retention of the laminate. Secondary tools can enlarge theholes (reaming or drilling) if the initial hole size cannot besufficiently enlarged to be at a final desired hole size following thedeformation operation. The deformation area can also be flattened byother tools to lower or change the deformation area profile.

[0262] The deformed region of the substrate is typically surrounding thethrough hole area. The deforming can occur on one or both sides of thelaminate and/or in an interior substrate layer(s), if present.

[0263] Punch tools have working surface(s). The working surface is thatpart of the punch tool that comes into contact with the laminate spacerarticle when using the punch tool.

[0264]FIGS. 8, 8a, 9, 10, 11, and 12 show cross-sections of varioustools that can be used to achieve some degree of deformation in thesubstrate layer(s) and displacement of the vibration damping material.The punches are disclosed in WO 96/21560 and U.S. Pat. No. 5,691,037,both assigned to the assignee of the present invention. These tools aretypically mounted in a stamping press that engages the tool to thelaminate spacer article surface(s) and applies the force to deform thesubstrate layer(s) and displace the vibration damping material in thedeformation area and to plastically deform the substrate(s) to achievethe improved fastening systems force retention.

[0265]FIG. 8 is a side view of an angled gripping feature “V” prior artpunch 274 with a blunt nose “V” protrusion 276 and angled grippingfeature 275 that can be used to make the deformed spacer article of theinvention.

[0266]FIG. 8A is a side view of an angled gripping feature “V” prior artpunch 279with a symmetrical blunt nose “V” protrusion 281 and angledgripping feature 284 that can be used to make the deformed spacerarticle of the invention. Also shown is angle (θ) 273 that is defined bythe intersection of a first line tangent to a gripping feature surfaceand a second line passing through the center of symmetry of theprotrusion but intersecting the first line at a point inside theprotrusion and inside the punch tool, on a side of the punch tool havingthe end. Also shown is angle (β) 277 that is defined by the intersectionof a first line tangent to a protrusion surface and a second linepassing through the center of symmetry of the protrusion, butintersecting the first line at a point outside the protrusion andoutside the punch tool, on a side of the punch tool having the end.

[0267]FIG. 9 is a side view of a strengthened angled gripping feature“V” prior art punch 300 with recessed frustoconical area 304 andrecessed conical areas 302 and 306 and strengthened, tapered side 307,and gripping feature 303 that can be used to make the deformed spacerarticle of the invention.

[0268]FIG. 10 is a side view of a prior art flat punch 324 with slotsand protrusions 326, 328, and 330 that can be used to make the deformedspacer article of the invention.

[0269]FIG. 12 is a side view of a strengthened, vented, angle-grippingfeature “V” prior art punch 340, with vent 348, gripping feature recess350, “V” protrusion 344, strengthened sides 341, outer diameter of punch342, gripping feature peak 351 that can be used to make deformed spacerarticles. FIG. 12 is the cross-section 12-12 of FIG. 11. FIG. 11 is thebottom view of the punch shown in FIG. 12.

[0270] Useful punches typically have an aspect of the tool that appliesforce in more than one direction to the laminate surface(s). Forexample, a first force may be applied by the tool at an angle to thelaminate spacer article surface and preferably at an angle towards thethrough hole of the intended deformation area. The gripping feature ofthe punch tool provides this first force. The force serves to pushmaterial to the through hole (substrate and vibration damping material)and also can prevent the substrate layer from slipping away from thethrough hole.

[0271] A second force may be applied in the hole area and is at an angledesigned to apply the most force in the downward direction and outwardfrom the through hole. The protrusion of the punch tool provides thissecond force. These two forces working together will concentrate thetool force in a manner to displace the vibration damping material massand deform the substrate(s).

[0272] The tool design is based on the substrate materials used, throughhole size, thickness of the laminate, thickness of each layer in alaminate, vibration damping material used and layer types in thelaminate. The punches used according to the invention may also have someunique requirements due to their design. For example, the punches mayrequire “venting” or “slotting” to allow escape of fluids used in thestamping process that can be entrapped in cavities or pockets the punchmay form between the punch end and the laminate during the tool's use.The entrapped fluid may not be highly compressible and can impede thepunch deformation of the laminate if not allowed to escape when underpressure. In addition, the punches may require added strength designs toprevent the tool from cracking, flexing, or having premature wear duringthe stamping process. The added strength or support to the punch may beadded by tapering the tool end to a wider shaft (tapering the shaftadjacent to the tool end). This will add strength to the grippingfeatures near an edge of the tool. The punches may also require a highergrade or different grade of tool steel to enhance the tool life then maytypically be used for other punch type processes on the laminate (forexample, piercing, embossing or coining).

[0273] The text handbook of metal forming (McGraw-Hill, Inc. Lange, ISBN0-07036285-8) gives a good overview of stamping processes and equipmentin general. Useful tool designs which accomplish the vibration dampingmaterial displacement and plastic deformation of the substrate layersinclude but are not limited to those tools that have flat, round, bullet(such as pointed conical, etc.), “V” (conical) or flat with a protrusionstyle punch design. These tool designs should be such that the majorityof the force is applied in the direction normal or perpendicular to thelaminate surface. This can require a flat, flat with a protrusion, around or a bullet punch to have a large radius as compared to thethrough hole and a “V” style punch with small angles to the horizontalof the laminate. Useful round, bullet, or flat style punches are thosewhich have a radius (or equivalent over sizing for non-round holes) atleast about 1.01 times greater than the through hole diameter,preferably at least about 1.5 times greater, and most preferably atleast about 2 times greater than the through hole diameter. The angle ofthe “V” style punch is typically from 1 degree to 89 degree as definedby the intersection of a first line tangent to the surface of the “V”protrusion and a second line parallel to a surface of the tool shaft andpassing through the center of the “V” type protrusion preferably from20-89degrees, and most preferably from 30-89 degrees.

[0274] Preferred tools are those that include a gripping features and atleast one protrusion. The preferred punch tool for preparing a deformedspacer article comprises a shaft having an end, wherein said endcomprises (i) at least one protrusion; and (ii) at least one grippingfeature. The gripping features are preferably selected from the groupconsisting of textured surfaces, continuous ridges, discontinuousridges, continuous ridges having textured surfaces, and discontinuousridges having textured surfaces.

[0275] The tools will deform the laminate in at least two maindirections. The direction of at least two of the forces generated by thepunch tools working surfaces are at angles to each other and theresultant forces or tool effect generates a displacement of thevibration damping material mass and plastic deformation of at least onesubstrate layer. The deformation of the substrate layer(s) alsopreferably limits the residual spring effect of the substrates, reducesvibration damping material recovery and reduces dynamic friction lossesduring use. This tool design should achieve at least about a 5% increasein attachment device force and/or torque and/or pressure and/or stressretention and may achieve greater than about a 35% improvement inretention as compared to a laminate spacer article with no displacementof the vibration damping material and plastic deformation of thesubstrate layers. The gripping feature(s) of the tool directs a portionof the laminate material in the area surrounding the hole in an angled(opposite the protrusion) direction. The resultant forces of this toolwill concentrate the forces in a fashion to displace the vibrationdamping material, provide for substrate deformation to reduce vibrationdamping material recovery, reduce substrate spring effect andpotentially reduce dynamic friction.

[0276] The punch tool's protrusions include but are not limited to thoseselected from the group consisting of frustoconical, elliptical,spherical, hemispherical, bullet-shaped, cylindrical, and conicalprotrusions and variations between these. The gripping features includebut are not limited to those selected from the group consisting of atextured surface(s), continuous ridges, discontinuous ridges, continuousridges having textured surfaces and discontinuous ridges having texturedsurfaces.

[0277] The tools used to displace the vibration damping material mayalso partially close or further open the hole during the deformationprocess. The hole diameter should be selected to take into account thetool design and the effect it has on the hole diameter so that theresultant spacer article has its intended dimensions.

[0278] The preferred tool design includes a symmetrical protrusion andgripping feature on the end of the tool. The protrusion has at least oneangle as defined by the intersection of a first line tangent to asurface of the protrusion and a second line passing through the centerof symmetry of the protrusion but intersecting the first line at a pointoutside the protrusion and outside the punch tool, on a side of thepunch tool having the end. The angle is between 0.5-89degrees,preferably is from 20-89degrees and most preferably from 30-89degrees.

[0279] The gripping feature has at least one angle as defined by theintersection of a first line tangent to a surface of the grippingfeature and a second line passing through the center of symmetry of theprotrusion but intersecting said first line at a point inside theprotrusion and inside the punch tool, on a side of the punch tool havingthe end. The angle is between 0.5-89degrees, preferably is from20-89degrees and most preferably from 30-89degrees. FIG. 8A is across-section showing an example of the angles, for a punch tool 279having angle β 277 of the protrusion 281 and angle θ 273 of the grippingfeature 284.

[0280] Furthermore, the tool is usefully designed such that thedeformation of the laminate as caused by the gripping feature of thetool occurs as the protrusion part of the tool is also deforming thelaminate. The tool should be designed to concentrate and build themechanical forces on the damping material to cause the damping materialsdisplacement and plastic deformation of the substrate.

[0281] Spacer Article Force Retention

[0282] The damped spacer article is preferably designed to have aninitial force retention value such that a later additional forceapplication step is not required. A spacer article without a forceretention of at least about 92% (as measured as described below) mayhave too great a loss of force retention after the initial forceapplication thus requiring additional force application to preventrotatable storage article slippage and/or movement during the driveoperation or shock event which could cause rotatable storage articledamage and/or loss of data. The force (pressure/torque/stress) retentionof the spacer article of the invention is preferably at least about 95%,more preferably at least about 97%, and most preferably at least about98.5%, as measured according to the test described later herein.

[0283] The spacer articles of the invention may optionally furthercomprise additional substrate layer(s), component(s), section(s), etc.,besides the substrate layers, substrate components, substrate sections,etc. In addition, the spacer article may also further compriseadditional vibration damping material layers, components, etc. Thearticle may optionally further comprise a bonding material layer(s) orring(s), for example. The bonding material may be bonded between thesubstrate and the vibration damping material, for example, or betweenmultiple substrates or between multiple vibration damping materiallayers or components, for example, wherein the storage modulus of thebonding material, is optionally higher than that of the vibrationdamping material to which it is bonded. Examples of useful bondingmaterials include but are not limited to those selected from the groupconsisting of epoxy resins and cyanoacrylates. Preferably, the storagemodulus of the bonding material layer or ring is less than that of asubstrate to which it is bonded.

[0284] Disk Drive Assembly

[0285] The present invention also provides a disk drive assembly havingat least one spacer article disclosed herein and at least one rotatablestorage article positioned on a spindle. A disk drive assembly can beprovided by first providing a disk drive, the disk drive having aspindle. A rotatable storage article may be positioned on the spindlesuch that the spindle extends through a through hole in the rotatablestorage article. A damped spacer article(s) of the invention may bepositioned on the spindle such that the spindle extends through athrough hole in the spacer article, wherein at least one spacer articleis positioned adjacent to and in contact with a rotatable storagearticle. Spacer articles may be positioned above and/or below rotatablestorage articles. Thus, the disk drive would have at least one rotatablestorage article and at least one spacer article positioned on the diskdrive spindle. Frequently the rotatable storage articles would alternatewith spacer articles on the spindle. Frequently an attachment devicesuch as a clamp would be used to hold the rotatable storage article(s)and spacer article(s) onto the spindle and under a holding force.

[0286] The holding force typically is in the range of at least about340,000 Pascals more typically about 340,000 to about 7,000,000. Pascalsand most typically about 1,000,000 Pascals to about 3,500,000 Pascals.Depending on the order in which they are placed on a spindle, arotatable storage article or spacer article may be directly under theattachment device. It is preferred that a rotatable storage article bepositioned so as to have a damped spacer article in contact with each ofits sides.

[0287]FIG. 5 illustrates a disk drive assembly of the inventioncomprising spindle base 52 and spindle 50 attached thereto. Rotatablestorage articles 42, 44, 43, 45, 47 and 49 are positioned on the spindle50. Damped spacer articles 46 and 48 are positioned therebetween. Spacerarticle 46 is similar to that of FIG. 4. Spacer article 48 is similar tothat of FIG. 6. Clamp 53, along with screws 51, holds the rotatablestorage articles 42, 44, 43, 45, 47, and 49 and spacer articles 46 and48 in place.

[0288]FIG. 7 illustrates an exploded view of the disk drive assembly ofFIG. 5.

[0289] A damped spacer article that has been cleaned and prepared forassembly into a drive preferably has an outgassing level of organic,organo-metallic, and metallic components that is preferably less thanabout 20 μg/cm², more preferably less than about 0.5 μg/cm² and mostpreferably less than 0.05 μg/cm when exposed to a temperature of 85° C.for 4 hours. Specific materials that are capable of outgassing include,but are not limited to: siloxanes, hydrocarbons, esters, organic acids,alcohols, amines, organo tins, amides, catalysts, and the like. It isalso preferable that any one category of components is less than 50weight % of the total and more preferably less than 10 weight % of thetotal outgassing level by weight. For example, it is preferable that thetotal amount of outgassed components would not include 50 weight percentor more of siloxanes.

[0290] The anion/ionic levels of the damped spacer article arepreferably below about 0.05 μg/cm², more preferably less than about 0.02μg/cm² and most preferably less than about 0.005 μg/cm². Specificcomponents that contribute to anion/ionic levels include: chloride,nitrate, nitrite, sulfate, fluoride, bromide, phosphate and the like. Itis also preferable than individual components are less than 50 weight %of the total, more preferably less than 10 weight % of the totaloutgassing level by weight.

[0291] Test Methods

[0292] The following test methods were used herein. A Laser Vibrometerwas configured to test the vibration levels of the storage disk mountedon a spindle. The spindle was attached to a vibrating shaker to excitethe resonances of the disks. The benefits of the damped spacers wasdetermined by reduction in vibration by measuring the RMS displacementof the disk over frequencies ranging from 200 Hz to 1,000 Hz whenexcited by the shaker and having damped spacer article or non-dampedspacer article in contact with the disk.

[0293] Determination of Vibration Acceleration and Disk Displacement

[0294] A laser vibrometer, Polytec Model PSV-200 scanning laservibrometer, was configured to test the vibration levels of a storagedisk mounted on a spindle. The spindle was attached to a vibratingshaker to excite the resonances of the mounted disk. The vibrationacceleration and displacement of an excited disk having a damped spacerarticle or a non-damped spacer article in contact with the disk weredetermined. The data was converted to the root mean square (RMS, i.e.,the square root of the arithmetic mean of the squares of a set ofnumbers). Optionally, amplitudes of various resonant peaks werecompared.

[0295] Equipment Setup

[0296]FIG. 36 illustrates the test equipment setup with the componentsnumbered as identified in the following section.

[0297] Laser Vibrometer Test Equipment

[0298]1101—Polytec Model PSV-200 scanning laser vibrometer

[0299]1102—Polytec Model OFV 3001 S vibrometer controller with 133 MHzPentium™ computer containing Polytec Version 5.2 controlling software

[0300]1103—MB Dynamics Model Modal 50 shaker

[0301]1104—MB Dynamics Model SS250VCF power amplifier

[0302]1105—Tektronix Model 2630 Personal Fourier Analyzer controlledwith a Toshiba Model T2200SX notebook computer

[0303]1106—PCB Model 208A05 force transducer

[0304]1107—PCB Model 482A16 signal conditioner

[0305]1108—Fluke Model 2100A digital thermometer with thermocouple

[0306]1109—Staco Model 3PN1010 variable transformer

[0307]1110—Sylvania Model 250R40/1 infrared heat lamp

[0308]1111—The Modal Shop Model 2050A lateral excitation stand

[0309]1112—spindle assembly

[0310] Double Spacer Test Fixture

[0311] An assembly of two spacer articles to be tested and two 0.81 mm(32 mils) thick aluminum rotatable storage articles was set on thespindle of a disk drive. The aluminum rotatable storage articles usedhad inner diameters (ID) of about 25 mm and outer diameters (OD) ofabout 95 mm. A 6.35 mm (0.25 inch) diameter hole was drilled in the topdisk to provide a line of sight for the laser beam to the second disk onwhich velocity measurements were made. The second rotatable storagearticle had a test spacer article on each side of it. The remainingspace on the spindle assembly was taken up by a cylindrical take-upspacer. The entire assembly was fixed to the spindle using athree-screwed spindle clamp. The spindle clamp was torqued to 1.5inch/ounces (0.01 Newtons meter) using a torque wrench. This set-up isillustrated in FIG. 37 as follows:

[0312]1201—laser beam

[0313]1202—aluminum rotatable storage article

[0314]1203—test spacers

[0315]1204—aluminum rotatable storage article measured

[0316]1205—spindle clamp

[0317]1206—cylindrical take-up spacer

[0318]1208—spindle flange

[0319]1210—force transducer

[0320]1212—shaker

[0321] Test Conditions

[0322] Input Force

[0323] A 2 volt chirp signal ranging from 100 Hz to 1,100 Hz with 8192time domain lines of resolution (4096 frequency domain lines) wasgenerated by the Tektronix Analyzer for input to the MB Dynamics poweramplifier. The level control setting for the power amplifier was ×2 andwas set at constant voltage, thus, imparting a RMS dynamic force of 8Newtons by the MB Dynamics shaker into the hub area of the spindle asmeasured by the PCB force transducer. The PCB signal conditioner was setto a gain of ×100.

[0324] Vibrometer Settings

[0325] Both the reference and vibrometer (A&B) channels were used tomeasure the input force and the velocity response. Magnitude averagingwas used with an average of three measurements used to determine thefrequency response function. The range setting for the vibrometer was125 mm/s/volt. No tracking filter was selected.

[0326] Frequency

[0327] A 1 kHz bandwidth was specified that resulted in a 2.56 kHzsample frequency in the time domain. Only data between 0.2 and 1 kHz wasused in the analysis. The antialias filter was used to minimize aliasingwhen the data was transformed from the time domain to the frequencydomain.

[0328] FFT or Time

[0329] The vibrometer was set at 3,200 lines of spectral resolution, ofwhich 2,561 lines were used to minimize leakage during thetransformation of the data from the time domain to frequency domain. Nowindowing was used on either the input or response channels of thevibrometer.

[0330] Trigger

[0331] The test was triggered off of the reference with the trigger setto a rising level of 5% of full scale and a pretrigger of 10% of thesample length.

[0332] Range

[0333] The range setting for the input (Channel A) was set at 5 voltswith a signal type setting of Force and a calibration of 44.56 Newtonsper volt. The range setting for the response (Channel B) was 10 Volts.

[0334] Measurement

[0335] A single frequency response function was determined from theaverage of three measurements taken near the outer edge of the seconddisk in the double disk assembly previously described. A small piece(0.5 sq. cm.) of 3M Type 7610 retro-reflective tape was placed on thedisk surface at the test point.

[0336] The frequency response function was then imported into aspreadsheet and integrated to convert from velocity to displacement. Thedisplacement was subjected to RMS analysis and reported inmicrons/Newton as a function of temperature in Table I (FIG. 40) andgraphically in FIG. 39.

[0337] A sample of the typical resonant peaks that the RMS analysis isused on is shown in FIG. 38.

[0338] Temperature Control

[0339] The temperature of the assembly was controlled with radiant heatfrom an infrared lamp controlled by a variable transformer. The lamp wasplaced at a 45 degree angle to the plane of the disk over the right halfof center at a distance of 5 cm from the surface of the disk.

[0340] Increments of 0 (transformer off), 40, 50, 60, 70 were used onthe transformer that produced temperatures of room temperature (settingof 0) and approximately 10-15 degrees C increments respectively,beginning at 45 degrees C, as measured in the hub area of the diskassembly.

[0341] Force Retention Test Method

[0342] To test the damped spacer article for force retentionperformance, a damped spacer article was set between two metal surfacesof an INSTRON force application and measurement system. An initial force(F_(I)) of between 1.24 MPa and 1.52 MPa (180 and 220 psi) was quicklyapplied (within about 0.2 to about 2 seconds) by lowering a mechanicalarm onto the spacer article being tested. A force gauge in the arm wasused to measure the force (F_(F)) periodically over 15 minutes. Thepercent of force retained (F_(R)) at 25° C. was determined asF_(R)=[(F_(I)−F_(F) )/F_(I)]×100.

EXAMPLES

[0343] The invention has been described with reference to variousspecific and preferred embodiments and will be further described byreference to the following detailed examples. It is understood, however,that there are many extensions, variations, and modifications on thebasic theme of the present invention, beyond that shown in the examplesand detailed description, which are within the spirit and scope of thepresent invention.

Examples 1-9and Comparative Examples 1-3

[0344] In order to evaluate the performance of various damped spacerarticles with good fastener force retention, various samples wereprepared.

[0345] Description of Sample

[0346] For the purpose of demonstrating the invention, threeviscoelastic damping materials were used in various spacer designs.

[0347] One damping material was an acrylic damping material (3M ISD-142,available from Minnesota Mining and Manufacturing Company, St. Paul,Minn.) that had a loss factor of greater than 0.2, a loss modulusgreater than 80,000 Pascals and a storage modulus of greater than 50,000Pascals at 1 Hz and 25-80°. It was used as an inner layer of a laminatespacer article (i.e., between two aluminum substrate layers) or as anexterior layer of the damped spacer article (i.e., attached to theoutside of an aluminum substrate layer).

[0348] A second damping material was a fluoroelastomer (FLUOREL FT-2481,available from Dyneon LLC Corp, Oakdale, Minn.) that had a loss modulus(G″) of less than 400,000, a storage modulus (G′) greater than 300,000Pascals, and a loss factor (tan delta) of less than 0.5 at 1 Hz and25-80° C.

[0349] A third damping material used was a nitrile viscoelastic polymerwith a Shore A hardness between 65-75 (available from C&C Packing, Inc.;White Bear Lake, Minn. under the tradename, AS-022 Buna N70).

Example 1

[0350] (Deformed Spacer Article)

[0351] A 0.051 mm thick layer of 3M ISD-142 was placed between twosubstrate layers of 1.1 mm thick aluminum. The damping material waslaminated onto one substrate layer and the second substrate layer wasplaced onto the damping material layer to create a laminate material.Modest pressure with a rubber roller was used to make the laminatematerial which was then processed through several stamping and grindingoperations as described below to form the internally damped spacerarticle of FIG. 13.

[0352] The laminate material was initially put into a mechanical pressthat applied significant pressure to the laminate material as it waspositioned between a die and punch. Press tonnage was between2.27-4.54×10⁴ kg (25-50 tons). The die/punch set-up was designed as toimpart a torque retention feature into the laminate material. After thepunch process, the laminate material was pierced to add the centerthrough hole, coined to impart a torque retention feature, blanked, andground to a final thickness of 2.2 mm to provide an internally dampedspacer article.

[0353] The damped spacer article was tested for damping performanceaccording to the test method “Determination of Vibration Accelerationand Disk Displacement” above. Results are given in FIG. 40/Table I andrepresented graphically in FIG. 39.

[0354] The damped spacer article was also tested for force retentionaccording to the test method “Force Retention Test Method” above. Thedata is in FIG. 42/Table II and graphically in FIG. 41.

Example 2

[0355] (High Modulus Vibration Damping Material Spacer)

[0356] A 0.051 mm thick layer of FLUOREL FT-2481 was placed between twopre-machined rings (25 mm inner diameter (ID), 31 mm outer diameter(OD)), that were each 1.1 mm thick aluminum. The damping material waslaminated onto one substrate ring layer and the second substrate layerwas placed onto the damping material layer to create an internallydamped spacer article of FIG. 35. Modest pressure and heat was appliedwith a vacuum pad applicator (107° C. (225° F.) for 30 minutes) toproduce a good bond between the aluminum rings and the FLUOREL FT2481.

[0357] The damped spacer article was tested for damping performanceaccording to the test method “Determination of Vibration Accelerationand Disk Displacement” above. Results are given in Table I andrepresented graphically in FIG. 39.

Example 3

[0358] (Back-to-back Spacer Article)

[0359] A spacer article similar to FIG. 24 comprising two channelcontaining damped spacer sections placed back-to-back was prepared asfollows:

[0360] An aluminum ring having an ID of 25 mm, an OD of 31 mm, and athickness of 1.1 mm was prepared by machining. Then, a continuouschannel was machined around the mid-circumference of the ring. Thechannel had an ID of 25.5 mm, an OD of 30.5 mm, and a depth of 0.10 mmand was centered in the ring.

[0361] A die-cut ring of 3M ISD-142 having an ID of 26.2 mm, an OD of29.6 mm, and a thickness of 0.127 mm was inserted into the channel inthe aluminum ring with hand pressure. The damping material layerextended beyond the plane of the top of the channel, so that contactcould be made with a disk when the spacer was placed against the disk ona spindle.

[0362] For this example, two spacer sections prepared above were placedback-to-back, thereby forming a spacer article of thickness 2.2 mm. Thespacer article was tested as in Example 2. Test results are given inTable I and represented graphically in FIG. 39.

[0363] The force retention of this spacer article was good, as it had adirect mechanical path for the force to be passed along through theclamp to the spacer article and to the disk and spindle base. Thisspacer article allowed the disk assembly to be easily disassembled,especially when the spacer articles may have adhered to the disk theycontacted due to the adhesive nature of the damping material layer.

Example 4

[0364] (Constrained Layer Damper Spacer Article)

[0365] The spacer article similar to FIG. 28 was prepared as Example 4.

[0366] An aluminum ring having an ID of 25 mm, an OD of 31.0 mm, and athickness of 2.2 mm was prepared by machining. Then, a continuous ledgewas machined around the circumference of the ring by cutting to a depthof 0.20 mm on both sides of the ring, from an ID on the ring of 28.0 mmto an OD of 31 mm. This created a torque retention feature of aprotrusion on the ID, on both sides of the ring.

[0367] Next, 0.127 mm thick 3M ISD-142 was laminated to 0.117 mm thickpolyester film (commercially available from 3M Company, St. Paul Minn.,as 3M SCOTCHPAK™ polyester film.) to provide a damping materiallaminate. The damping material laminate was then die-cut in a ringhaving an OD of 30.5 mm and an ID of 28.65 mm. This damping materiallaminate ring was placed on each side of the continuous ledge of thealuminum ring. The thickness of the damping material laminate ring wasgreater than the depth of the ledge so that the laminate ring extendedbeyond the plane of the top of the protrusion. This allowed for contactwith that portion of a disk it is placed against when used in a diskdrive assembly and under slight compression.

[0368] The spacer article was tested as in Example 1. Test results aregiven in Tables I and II and represented graphically in FIGS. 39and 41.

Example 5

[0369] (Segmented Constrained Layer Damped Spacer Article)

[0370] A spacer article somewhat similar to that of FIG. 27 was preparedas Example 4, except for the following differences:

[0371] The damped spacer article was made in the same manner as Example4, except that the damping material laminate used was cut into four nearequal size sections, each approximately 0.90 to 0.95 times the size ofone quarter of the ring. Four sections were placed on each side of thecontinuous ledge of the aluminum ring approximately equally spaced apartfrom each other.

[0372] The spacer article was tested as in Example 2. Test results aregiven in Table I and represented graphically in FIG. 39.

Example 6

[0373] (Sideways U-Shaped Spacer Article)

[0374] A spacer article similar to that of FIG. 29 was prepared asfollows:

[0375] An aluminum spacer that was 2.2 mm thick, 25 mm ID and 31 mm ODwas machined to remove the internal aluminum portion from the OD intothe ID until the desired notching or cut-out was complete. On a lathe,the aluminum was removed from the OD beginning at a depth from each sideof the ring of 0.254 mm. The cut into the spacer extended from the OD of31.0 mm to an ID of 26.6 mm.

[0376] An “O” ring-shaped vibration damping material component was thenmolded to provide a part that had the dimensions of approximately 1.7 mmdiameter and an ID of 25.5 mm and OD of 29.0 mm. The vibration dampingmaterial component was molded from AS-022 Buna N70.

[0377] The vibration damping material component was placed into theinset cut-out of the aluminum ring. The spacer article was tested as inExample 1. Test results are given in Tables I and II and FIGS. 38 and41.

Example 7

[0378] (Constrained Layer Damper Spacer Article)

[0379] A spacer article similar to that of FIG. 28 was prepared as inExample 4 except for the following differences:

[0380] An aluminum ring having an ID of 25 mm, an OD of 31.0 mm, and athickness of 2.2 mm was prepared by machining. Then, a continuous ledgewas machined around the circumference of the ring by cutting to a depthof 0.20 mm on both sides of the ring, from an ID on the ring of 27.5 mmto an OD of 31 mm. This created a torque retention feature of aprotrusion on the ID, on both sides of the ring.

[0381] A 0.127 mm thick 3M ISD-142 was laminated to 0.117 mm thickSCOTCHPAK™ polyester film to provide a constrained damping materiallaminate. The damping material laminate was then die-cut in a ringhaving an OD of 30.5 mm and an ID of 28.65 mm. This damping materiallaminate ring was placed on each side of the continuous ledge of thealuminum ring. The thickness of the damping material laminate ring wasgreater than the depth of the ledge so that the laminate ring extendedbeyond the plane of the top of the protrusion. This allowed for contactwith that portion of a disk it was placed against when used in a diskdrive assembly and slight compression.

[0382] The spacer article was tested as in Example 2. Test results aregiven in Table I and represented graphically in FIG. 39.

Example 8

[0383] (Deformed Spacer Article)

[0384] A 0.051 mm thick layer of 3M ISD-142 was placed between twosubstrate layers of 1.1 mm thick aluminum. The damping material waslaminated onto one substrate layer and the second substrate layer wasplaced onto the damping material layer to create a laminate material.Modest pressure with a rubber roller was used to make the laminatematerial that was then processed through several stamping and grindingoperations as described below to form the internally damped spacerarticle similar to that of FIG. 17.

[0385] The laminate material was initially put into a mechanical pressthat applied significant pressure to the laminate material as it waspositioned between a die and punch. Press tonnage was between2.27-4.54×10⁴ kg (25-50 tons). The die/punch set-up was designed as toimpart a torque retention feature into the laminate material. After thepunch process, the laminate material was pierced to add the centerthrough hole, coined to impart a torque retention feature, and ground toa final thickness of 2.2 mm to provide an internally damped spacerarticle.

[0386] The spacer article was tested for force retention according tothe test method hereinabove. Results are given in Table II andrepresented graphically in FIG. 41.

Example 9

[0387] (Constrained Layer Damper Spacer Article)

[0388] The spacer article of FIG. 28 was prepared similar to Example 4,except for the following differences:

[0389] An aluminum ring having an ID of 25 mm, an OD of 31.0 mm, and athickness of 2.2 mm was prepared by machining. Then, a continuous ledgewas machined around the circumference of the ring by cutting to a depthof 0.20 mm on both sides of the ring, from an ID on the ring of 28.0 mmto an OD of 31 mm. This created a torque retention feature of aprotrusion on the ID, on both sides of the ring.

[0390] Next, 0.127 mm thick 3M ISD-142 was laminated to 0.117 mm thick3M SCOTCHPAK™ polyester film to provide a damping material laminate. Thedamping material laminate was then die-cut in a ring having an OD of30.5 mm and an ID of 29.28 mm. This damping material laminate ring wasplaced on each side of the continuous ledge of the aluminum ring. Thethickness of the damping material laminate ring was greater than thedepth of the ledge so that the laminate ring extended beyond the planeof the top of the protrusion. This allowed for contact with that portionof a disk it is placed against when used in a disk drive assembly underslight compression.

[0391] The spacer article was tested as in Example 8. Test results aregiven in Table II and represented graphically in FIG. 41.

Comparative Example 1

[0392] (Standard Aluminum Spacer Article)

[0393] Comparative Example 1 was a standard machined aluminum spacerarticle from a commercial disk drive assembly, which had a thickness of2.2 mm, an ID of 25 mm, and an OD of 31 mm.

Comparative Example 2

[0394] (Internally Damped Spacer Article)

[0395] A 0.025 mm thick layer of 3M ISD-142 was placed between twopre-machined rings (25 mm ID, 31 mm OD) that were each 2.7 mm thickaluminum. The damping material was laminated onto one substrate ringlayer and the second substrate layer was placed onto the dampingmaterial layer to create an internally damped laminate material. Modestpressure was applied to produce a good bond between the aluminum ringsand 3M ISD-142 to form the spacer article similar to FIG. 2, but with noforce retention fibers or particulate. No means for force retention wasused. The spacer article was tested as in Example 8. Test results aregiven in Table II and represented graphically in FIG. 41.

Comparative Example 3

[0396] (Internally Damped Spacer Article)

[0397] A 0.051 mm thick layer of 3M ISD-142 was placed between twopre-machined rings (25 mm ID, 31 mm OD) that were each 2.7 mm thickaluminum. The damping material was laminated onto one substrate ringlayer and the second substrate ring layer was placed onto the dampingmaterial layer to create an internally damped laminate material. Modestpressure was applied to produce a good bond between the aluminum ringsand 3M ISD-142 to form the spacer article but without high modulusvibration damping material. No means for force retention was used. Thespacer article was tested as in Example 8. Test results are given inTable II and represented graphically in FIG. 41.

[0398] The data in FIG. 39 is graphically represented in Table I of FIG.40. Table I clearly shows the reduction in displacement of a disk when adamped spacer article of the invention was used as opposed to thestandard aluminum spacer article (Comparative Ex. 1).

[0399] The data clearly shows that for a damped spacer article without aforce retention means (either mechanical design or polymer design),significant force loss occurs as is shown in FIG. 41 and Table II ofFIG. 42.

[0400] The damped spacer article of the invention can offer thepotential to reduce the RMS (200-1000 Hz) from a few percent to 40percent or more, depending on the reduction in RMS needed to improve thedrive's reading and writing performance at the drive operatingtemperature. The RMS analysis could also be expanded beyond 200-1000 Hz,depending on the disk type tested with the damped spacer articledesigns. Disks that have lower or higher natural frequencies due totheir design would potentially cause the RMS range to be shifted so thatthe dominate resonant vibration peaks are included in the analysis.These mode shapes include the 1,0 and 0,1 vibration modes and alsoinclude modes such as the 1,1; 2,2; 1,2, etc. Modes of most importancetend to be below the 5,5 mode vibration shape. When disks of differentmodulus and dimensions are used, the vibration mode frequencies canshift, changing the range of RMS selection to include the dominatevibration modes that effect the drives reading and writing performance.

[0401] The spacer designs also provide a design that offers high forceretention of the means for securing the rotatable storage article andspacer article onto the spindle that is applying force to hold the disksand spacers on the spindle from slipping during operation and or highshock or vibration conditions that the drive may encounter duringoperation or shipping and handling or non-operating shock. The spacersare designed to provide at least 93% of the force retention of thestandard aluminum spacer, preferably greater than 95%, more preferablygreater than 97% and most preferably greater than 98.5%. Designs thatfail to have a force retention means at the desired force retentionlevel will allow a drive to fail.

[0402] A spacer article of the invention preferably is designed andpositioned adjacent to a rotatable storage article such that is thatdoes not cause any warpage, kinking, high spots, crimps, dents, bends ordeflections of the rotatable storage articles as measured by alaser/optical device that tests for flatness (peak to valley, RMS,etc.). The peak to valley measurement of a rotatable storage articlewith the damped spacer secured to it is useful for drive read andwriting use plus reliability, etc.) if the peak to valley measurementacross the disk read and writing surface area is less than 20 microns,preferably less than 10 microns, more preferably less than 7 microns,and most preferably less than 5 microns. The disk drive assembly can betested in various optical flatness metrology test systems, such as aZYGO MESA Flatness measuring tool, available from ZYGO Corporation;Middlefield, Conn.

[0403] Preferably the components of the disk drive assembly are selectedand assembled such that the rotatable storage article has a flatness ofpreferably less than about 20 microns, more preferably less than about10 microns, most preferably less than about 5 microns and an improvementof disk vibration RMS by at least about a 10%, preferably at least about20%, most preferably by at least about 30 percent reduction and a forceretention of at least about 93% as compared to a standard spacer in thesame spindle and clamping means, and more preferably at least about 97%.

[0404] The foregoing detailed description and example have been givenfor clarity of understanding only. No unnecessary limitations are to beunderstood therefrom. The invention is not limited to the exact detailsshown and described, for variations obvious to one skilled in the artwill be included within the invention defined by the claims.

It is claimed:
 1. A spacer article comprising: (i) a laminate having athrough hole therein, the laminate comprising: an upper substrate layerand a lower substrate layer; a layer of vibration damping materialcomprising a viscoelastic material positioned between said upper andlower substrate layers; wherein the storage modulus of each substratelayer is greater than that of the viscoelastic material in the vibrationdamping material layer; and (ii) a substrate component having a throughhole, wherein the storage modulus of the substrate component is greaterthan that of the viscoelastic material in the vibration damping materiallayer, wherein one of (I) or (II) is true: (I) the laminate ispositioned within the through hole of the substrate component and ispress fit into the substrate component; (II) the substrate component ispositioned within the through hole of the laminate and is press fit intothe laminate; wherein for both (I) and (II) the laminate has an uppersurface and a lower surface and the substrate component has an uppersurface and a lower surface, wherein the laminate has a thickness andthe substrate component has a thickness, and the thickness and positionof the laminate is such that the laminate upper surface ranges frombeing about 10 percent of the height of the substrate component belowthe upper surface of the substrate component to about 10 percent of theheight of the substrate component above the substrate component and suchthat the laminate lower surface ranges from being about 10 percent ofthe height of the substrate component above the lower surface of thesubstrate component to about 10 percent of the height of the substratecomponent below the lower surface of the substrate component, andwherein the spacer article has a through hole.
 2. The spacer article ofclaim 1 wherein the thickness and position of the laminate is such thatthe laminate upper surface ranges from being about 5 percent of theheight of the substrate component below the upper surface of thesubstrate component to about 5 percent of the height of the substratecomponent above the substrate component and such that the laminate lowersurface ranges from being about 5 percent of the height of the substratecomponent above the lower surface of the substrate component to about 5percent of the height of the substrate component below the lower surfaceof the substrate component.
 3. The spacer article of claim 1 wherein thethickness and position of the laminate is such that the laminate uppersurface ranges from being about 2 percent of the height of the substratecomponent below the upper surface of the substrate component to about 2percent of the height of the substrate component above the substratecomponent and such that the laminate lower surface ranges from beingabout 2 percent of the height of the substrate component above the lowersurface of the substrate component to about 2 percent of the height ofthe substrate component below the lower surface of the substratecomponent.
 4. The spacer article of claim 1 wherein the spacer articlehas a force retention of at least about 92 percent of an initialcompression force of 1.4×10⁶ Pascals applied to the spacer article forabout 0.2 to about 2 seconds at about 25° C. at about 15 minutes afterthe application of the initial compression force.
 5. A disk driveassembly comprising: (a) a disk drive, the disk drive having a spindle;(b) a rotatable storage article positioned such that the spindle extendsthrough a through hole in the rotatable storage article; (c) the spacerarticle of claim 1 , wherein the spacer article is positioned such thatthe spindle extends through the through hole in the spacer article,wherein the spacer article is positioned adjacent to and in contact withthe rotatable storage article; and (d) a means for securing therotatable storage article and spacer article onto the spindle.
 6. Aspacer article comprising: (a) a first substrate having a through holetherein, the first substrate having an upper surface and a lowersurface, an inner side and an outer side, wherein the inner side has agroove therein; (b) a second substrate having a through hole therein,the second substrate having an upper surface and a lower surface, aninner side and an outer side, wherein the outer side has a groovetherein; wherein the second substrate is positioned within the throughhole of the first substrate, wherein the inner side of the firstsubstrate having a groove therein faces the outer side of the secondsubstrate having a groove therein; wherein the first substrate andsecond substrate each have a height such that the height of the firstsubstrate is within a range of about 90 percent of the height of thesecond substrate to about 110 percent of the height of the secondsubstrate; (c) a vibration damping material component having a throughhole therein, the vibration damping material component comprising aviscoelastic material, the vibration damping material component having asurface area, wherein the vibration damping material component ispositioned within the through hole of the first substrate between thefirst substrate and the second substrate, wherein at least about 10percent of the surface area of the vibration damping material componentis in contact with the grooves; wherein the storage modulus of both thefirst substrate and the second substrate is greater than that of theviscoelastic material in the vibration damping material component;wherein the spacer article has a through hole therein; wherein thevibration damping material component is at least about 5 percent of theheight of the first substrate beneath the upper surface of the firstsubstrate and at least about 5 percent of the height of the firstsubstrate above the lower surface of the first substrate; and whereinthe vibration damping material component is at least about 5 percent ofthe height of the second substrate beneath the upper surface of thesecond substrate and at least about 5 percent of the height of thesecond substrate above the lower surface of the second substrate.
 7. Thespacer article of claim 6 wherein the vibration damping materialcomponent is at least about 10 percent of the height of the firstsubstrate beneath the upper surface of the first substrate and at leastabout 10 percent of the height of the first substrate above the lowersurface of the first substrate; and wherein the vibration dampingmaterial component is at least about 10 percent of the height of thesecond substrate beneath the upper surface of the second substrate andat least about 10 percent of the height of the second substrate abovethe lower surface of the second substrate.
 8. The spacer article ofclaim 6 wherein the vibration damping material component is at leastabout 15 percent of the height of the first substrate beneath the uppersurface of the first substrate and at least about 15 percent of theheight of the first substrate above the lower surface of the firstsubstrate; and wherein the vibration damping material component is atleast about 15 percent of the height of the second substrate beneath theupper surface of the second substrate and at least about 15 percent ofthe height of the second substrate above the lower surface of the secondsubstrate.
 9. The spacer article of claim 6 wherein the first substrate,vibration damping material component, and second substrate arepositioned such that the first substrate and second substrate are offsetfrom each other.
 10. The spacer article of claim 9 wherein the uppersurface of the first substrate and the upper surface of the secondsubstrate are offset from each other by about 0.025 to about 0.5 mm andwherein the lower surface of the first substrate and the lower surfaceof the second substrate are offset from each other by about 0.025 toabout 0.5 mm.
 11. The spacer article of claim 9 wherein the uppersurface of the first substrate and the upper surface of the secondsubstrate are offset from each other by about 0.025 to about 0.2 mm andwherein the lower surface of the first substrate and the lower surfaceof the second substrate are offset from each other by about 0.025 toabout 0.2 mm.
 12. The spacer article of claim 6 wherein the firstsubstrate is substantially ring-shaped, the second substrate issubstantially ring-shaped, and the vibration damping material issubstantially ring-shaped.
 13. The spacer article of claim 6 wherein theheight of the first substrate is within a range of about 95 percent ofthe height of the second substrate to about 105 percent of the height ofthe second substrate.
 14. The spacer article of claim 6 wherein thefirst substrate and second substrate are about the same height.
 15. Thespacer article of claim 6 wherein at least about 25 percent of thesurface area of the vibration damping material component is in contactwith the grooves.
 16. The spacer article of claim 6 wherein at leastabout 50 percent of the surface area of the vibration damping materialcomponent is in contact with the grooves.
 17. The spacer article ofclaim 6 wherein at least about 70 percent of the surface area of thevibration damping material component is in contact with the grooves. 18.The spacer article of claim 6 wherein the first substrate and secondsubstrate are within at least about 0.254 mm of each and at least about85% of the surface area of the vibration damping material component fitsentirely within a cavity defined by the groove in the first substrateand the groove in the second substrate.
 19. A disk drive assemblycomprising: (a) a disk drive, the disk drive having a spindle; (b) arotatable storage article positioned such that the spindle extendsthrough a through hole in the rotatable storage article; (c) a spacerarticle, wherein the spacer article is positioned such that the spindleextends through a through hole in the spacer article, wherein the spacerarticle is positioned adjacent to and in contact with the rotatablestorage article; wherein the spacer article comprises: a laminate havinga through hole, the laminate comprising: (i) an upper substrate layerand a lower substrate layer; (ii) a layer of vibration damping materialcomprising a viscoelastic material positioned between said upper andlower substrate layers; wherein the storage modulus of each substratelayer is greater than that of the viscoelastic material in the vibrationdamping material layer; wherein at least one deformation area is presentin said spacer wherein a deformation area is an area of the spacerarticle wherein at least one substrate layer is plastically deformedsuch that the upper and lower substrate layers are touching orpositioned closer to each other than in an area of the spacer article inwhich none of the substrates are plastically deformed; and wherein in atleast 1 vibration damping material layer, within at least a 0.5% area ofthe deformation area, the vibration damping material is non-existent or,if present, has a mass that is 90% or less than the average mass of thevibration damping material layer of an equal area in an area of thespacer article which is not in a deformation area.
 20. The disk driveassembly of claim 19 wherein the spacer article has a force retention ofat least about 92 percent of an initial compression force of 1.4×10⁶Pascals applied to the spacer article for about 0.2 to about 2 secondsat about 25° C. at about 15 minutes after the application of the initialcompression force.
 21. The disk drive assembly of claim 19 wherein thespacer article is substantially in the shape of a ring.
 22. The diskdrive assembly of claim 19 wherein at least one substrate layer selectedfrom the group consisting of the first and second substrate layers hasat least one of the following features selected from the groupconsisting of protrusions, recessions, bevels, indentations, ledges,coins, ridges and notches in at least one deformation area.
 23. The diskdrive assembly of claim 19 wherein at least one substrate layer has avariable thickness in a deformation area.
 24. The disk drive assembly ofclaim 19 wherein the vibration damping material layer within at least a0.5% area of the deformation area, is nonexistent or, if present, has amass that is 50% or less than the average mass of the vibration dampingmaterial layer in an equal area of the spacer article which is not adeformation area.
 25. A disk drive assembly comprising: (a) a diskdrive, the disk drive having a spindle; (b) a rotatable storage articlepositioned such that the spindle extends through a through hole in therotatable storage article; (c) a spacer article, wherein the spacerarticle is positioned such that the spindle extends through a throughhole in the spacer article, wherein the spacer article is positionedadjacent to and in contact with the rotatable storage article; whereinthe spacer article comprises: a laminate having a through hole, thelaminate comprising: (i) an upper substrate layer and a lower substratelayer; (ii) a layer of vibration damping material comprising aviscoelastic material positioned between said upper and lower substratelayers, wherein the viscoelastic material has a loss modulus of lessthan about 500,000 Pascals, a storage modulus greater than about 200,000Pascals and a loss factor of less than about 0.5 when measured at 1Hertz and between 25 and 80° C.; wherein the storage modulus of eachsubstrate layer is greater than that of the viscoelastic material in thevibration damping material layer; and (d) a means for securing therotatable storage article and spacer article onto the spindle, whereinthe spacer article has a force retention of at least about 92 percent ofan initial compression force of 1.4×10⁶ Pascals applied to the spacerarticle for about 0.2 to about 2 seconds at about 25° C. at about 15minutes after the application of the initial compression force.
 26. Thedisk drive assembly of claim 25 wherein the spacer article has a forceretention of at least about 95 percent of an initial compression forceof 1.4×10⁶ Pascals applied to the spacer article for about 0.2 to about2 seconds at about 25° C. at about 15 minutes after the application ofthe initial compression force.
 27. The disk drive assembly of claim 25wherein the loss factor of the viscoelastic material is less than 0.4,the loss modulus is less than about 400,000 Pascals, and the storagemodulus is greater than about 200,000 Pascals when measured at 1 Hertzand between 25 and 80° C.
 28. A disk drive assembly comprising: (a) adisk drive, the disk drive having a spindle; (b) a rotatable storagearticle positioned such that the spindle extends through a through holein the rotatable storage article; (c) a spacer article, wherein thespacer article is positioned such that the spindle extends through athrough hole in the spacer article, wherein the spacer article ispositioned adjacent to and in contact with the rotatable storagearticle; wherein the spacer article comprises: a laminate, the laminatehaving a through hole therein, wherein the laminate comprises: (i) anupper substrate layer and a lower substrate layer; (ii) a layer ofvibration damping material comprising a viscoelastic material positionedbetween said upper and lower substrate layers; wherein the storagemodulus of each substrate layer is greater than that of the viscoelasticmaterial in the vibration damping material layer; and wherein the spacerarticle is welded such that the upper substrate is welded to the lowersubstrate; and wherein when the rotatable storage article and spacerarticle are positioned on the spindle, a force applied onto the spacerarticle by virtue of an attachment device is less than the Young'smodulus of the vibration damping material.
 29. The disk drive assemblyof claim 28 wherein the spacer article has a force retention of at leastabout 92 percent of an initial compression force of 1.4×10⁶ Pascalsapplied to the spacer article for about 0.2 to about 2.0 seconds atabout 25° C. at about 15 minutes after the application of the initialcompression force.
 30. A disk drive assembly comprising: (a) a diskdrive, the disk drive having a spindle; (b) a rotatable storage articlepositioned such that the spindle extends through a through hole in therotatable storage article; (c) a spacer article, wherein the dampedspacer article is positioned such that the spindle extends through athrough hole in the spacer article, wherein the spacer article ispositioned adjacent to and in contact with the rotatable storagearticle; wherein the spacer article comprises: an upper substrate layerand a lower substrate layer; a layer of vibration damping materialcomprising a viscoelastic material positioned between said upper andlower substrate layers; wherein the storage modulus of each substratelayer is greater than that of the viscoelastic material in any vibrationdamping material layer with which it is in contact; wherein thevibration damping material layer of the spacer article further comprisesan additive selected from the group consisting of fibers, particulates,and mixtures thereof; wherein the total amount of additive is about 1 toabout 95 weight percent based upon the total weight of the vibrationdamping material; wherein the particulate size ranges from about 0.05 toabout 125% of the average thickness of the vibration damping materiallayer in which the particulate is present; wherein the fiber diameterranges from about 0.05 to about 125% of the average thickness of thevibration damping layer in which the fiber is present; wherein the loadbearing capacity of the additive is at least about 700,000 Pascals; and(d) a means for securing the rotatable storage article and spacerarticle onto the spindle, wherein a force applied onto the spacerarticle by virtue of the attachment device is less than the Young'smodulus of the vibration damping material.
 31. The disk drive assemblyof claim 30 wherein the spacer article is substantially in the shape ofa ring.
 32. The disk drive assembly of claim 30 wherein the spacerarticle has a force retention of at least about 92 percent of an initialcompression force of 1.4×10⁶ Pascals applied to the spacer article forabout 0.2 to about 2 seconds at about 25° C. at about 15 minutes afterthe application of the initial compression force.
 33. A spacer articlecomprising: two spacer sections, each spacer section having a throughhole, each spacer section independently comprising: (a) a substratewherein the substrate comprises (i) a base, the base having two opposingmajor surfaces which are a first surface and a second surface; and (ii)at least one side, each side having a height, wherein the side(s) arejoined to the first surface of the base; (b) a vibration dampingmaterial comprising a viscoelastic material, wherein the substrate has ahigher storage modulus than the viscoelastic material in the vibrationdamping material, wherein the vibration damping material is bonded tothe first surface of the base, wherein the vibration damping materialhas a height great enough such that it is about 90 to about 300 percentof the height of a highest substrate side; wherein the spacer articlehas a through hole therein; and wherein the second surface of the baseof one spacer section is positioned against the second surface of thebase of the other spacer section.
 34. The spacer article of claim 33wherein the vibration damping material has a height great enough suchthat it is about 100 to about 200 percent of the height of the highestsubstrate side.
 35. The spacer article of claim 33 wherein the vibrationdamping material has a height great enough such that it is about 102 toabout 150 percent of the height of the highest substrate side.
 36. Thespacer article of claim 33 wherein the vibration damping material has aheight great enough such that it is about 102 to about 120 percent ofthe height of the highest substrate side.
 37. The spacer article ofclaim 33 wherein for each spacer section the base is substantially inthe shape of a ring, the ring having an inner edge and an outer edge,and wherein the substrate has two sides, wherein one side is in the formof a ring and is joined to the first surface of the base at about theinner edge of the base and the second side is in the form of a ring andis joined to the first surface of the base at about the outer edge ofthe ring in order to from a channel and the vibration damping materialis at least partially contained within the channel.
 38. The spacerarticle of claim 1 wherein each substrate section is substantially inthe shape of a ring.
 39. The disk drive assembly of claim 33 wherein thesecond surfaces of the bases of both spacer sections are interlocking.40. The spacer article of claim 33 wherein the spacer article has aforce retention of at least about 92 percent of an initial compressionforce of 1.4×10⁶ Pascals applied to the spacer article for about 0.2 toabout 2 seconds at about 25° C. at about 15 minutes after theapplication of the initial compression force.
 41. A disk drive assemblycomprising: (a) a disk drive, the disk drive having a spindle; (b) arotatable storage article positioned such that the spindle extendsthrough a through hole in the rotatable storage article; (c) the spacerarticle of claim 33 , wherein the spacer article is positioned such thatthe spindle extends through the through hole in the spacer article,wherein the spacer article is positioned adjacent to and in contact withthe rotatable storage article; and (d) an attachment device securing therotatable storage article and spacer article onto the spindle.
 42. Aspacer article comprising: (a) two substrate sections which areidentified as a first substrate section and a second substrate section,wherein the first substrate section has a through hole, wherein thefirst substrate section comprises a base and a side joined to the basewhich extends above and below the base, wherein the side has a heightand wherein the side has an upper surface and a lower surface, whereinthe side defines an outer perimeter of the first substrate section andthe base defines an inner perimeter of the first substrate section,wherein the second substrate section has a through hole, wherein thesecond substrate section comprises a base and a side joined to the basewhich side extends above and below the base, wherein the side has aheight and wherein the side has an upper surface and a lower surface,wherein the base defines an outer perimeter of the substrate section andthe side defines an inner perimeter of the substrate section, whereinthe second substrate section fits within the through hole of the firstsubstrate section, wherein the side of the first substrate section has aheight which falls within a range of about 90 percent of the height ofthe side of the second substrate to a height about 110 percent of theheight of the side of the second substrate; (b) a vibration dampingmaterial comprising viscoelastic material; wherein the storage modulusof the substrate sections are greater than the viscoelastic material inthe vibration damping material; wherein the two substrate sections arejoined together via the vibration damping material laminated between thebases of the two substrate sections, wherein the substrate sections arejoined such that upper surface of the side of the first substratesection is not greater than about 10 percent of the height of the sideof the second substrate section above the upper surface of the side ofthe second substrate section nor greater than about 10 percent of theheight of the side of the second substrate section below the uppersurface of the side of the second substrate; wherein the substratesections are joined such that lower surface of the first substratesection is not greater than about 10 percent of the height of the sideof the second substrate section above the lower surface of the side ofthe second substrate section nor greater than 10 percent of the heightof the side of the second substrate below the lower surface of the sideof the second substrate; and wherein the spacer article has a throughhole therein.
 43. The spacer article of claim 42 having a forceretention of at least about 92 percent of an initial compression forceof 1.4×10⁶ Pascals applied to the spacer article for about 0.2 to about2 seconds at about 25° C. at about 15 minutes after the application ofthe initial compression force.
 44. The spacer article of claim 42wherein the substrate sections are joined such that upper surface of theside of the first substrate section is not greater than about 5 percentof the height of the side of the second substrate section above theupper surface of the side of the second substrate section nor greaterthan about 5 percent of the height of the side of the second substratesection below the upper surface of the side of the second substrate; andwherein the substrate sections are joined such that lower surface of thefirst substrate section is not greater than about 5 percent of theheight of the side of the second substrate section above the lowersurface of the side of the second substrate section nor greater than 5percent of the height of the side of the second substrate below thelower surface of the side of the second substrate.
 45. The spacerarticle of claim 42 wherein the upper surface of the side of the firstsubstrate section is level with the upper surface of the side of thesecond substrate section and wherein the lower surface of the side ofthe first substrate section is level with the lower surface of the sideof the second substrate section.
 46. The spacer article of claim 42wherein each spacer section is substantially ring shaped and the spacerarticle is substantially ring shaped.
 47. A disk drive assemblycomprising: (a) a disk drive, the disk drive having a spindle; (b) arotatable storage article positioned such that the spindle extendsthrough a through hole in the rotatable storage article; (c) the spacerarticle of claim 42 , wherein the spacer article is positioned such thatthe spindle extends through a through hole in the spacer article,wherein the spacer article is positioned adjacent to and in contact withthe rotatable storage article; and (d) a means for securing therotatable storage article and spacer article onto the spindle.
 48. Aspacer article comprising (a) a substrate, the substrate comprising (i)a base the base having two major opposing surfaces, an upper surface anda lower surface, and (ii) at least one side joined to the upper surfaceof the base, each side having a height; and (b) a first constrainedlayer damper attached to the upper surface of the base wherein the firstconstrained layer damper has a height such that it ranges from beingabout 90 to about 300 percent of the height of the side having agreatest height on the upper surface of the base; wherein eachconstrained layer damper independently comprises: (i) a constraininglayer; (ii) a layer of vibration damping material bonded to theconstraining layer, wherein the vibration damping material comprisesviscoelastic material; wherein the storage modulus of the constraininglayer is greater than that of the viscoelastic material in the vibrationdamping material; wherein each constrained layer damper is attached tothe base via its vibration damping material layer; and wherein thespacer article has a through hole therein.
 49. The spacer article ofclaim 48 which further comprises (iii) at least one side joined to thelower surface of the base, each side having a height; and (c) a secondconstrained layer damper attached to the lower surface of the basewherein the second constrained layer damper has a height such that itranges from being about 90 to about 300 percent of the height of theside having a greatest height on the lower surface of the base, whereinthe second constrained layer damper independently comprises: (i) aconstraining layer; (ii) a layer of vibration damping material bonded tothe constraining layer, wherein the vibration damping material comprisesviscoelastic material, wherein the storage modulus of the constraininglayer is greater than that of the viscoelastic material in the vibrationdamping material; and wherein the storage modulus of the constraininglayer is greater than that of the viscoelastic material in the vibrationdamping material; wherein each constrained layer damper is attached tothe base via its vibration damping material layer.
 50. The spacerarticle of claim 48 wherein said constrained layer damper has a heightsuch that it ranges from being about 95 to about 200 percent of theheight of the side having a greatest height on the lower surface of thebase.
 51. The spacer article of claim 49 wherein said constrained layerdamper has a height such that it ranges from being about 95 to about 200percent of the height of the side having a greatest height on the lowersurface of the base.
 52. The spacer article of claim 58 wherein thespacer article has a force retention of at least about 92 percent of aninitial compression force of 1.4×10⁶ Pascals applied to the spacerarticle for about 0.2 to about 2 seconds at about 25° C. at about 15minutes after the application of the initial compression force.
 53. Thespacer article of claim 49 wherein the first constrained layer damperhas a height about 0.01 to about 0.5 mm greater than the height of theside having the greatest height on the upper surface of the base andwherein the second constrained layer damper has a height about 0.01 toabout 0.5 mm greater than the height of the side having the greatestheight on the lower surface of the base.
 54. A disk drive assemblycomprising: (a) a disk drive, the disk drive having a spindle; (b) arotatable storage article positioned such that the spindle extendsthrough a through hole in the rotatable storage article; (c) the dampedspacer article of claim 48 , wherein the damped spacer article ispositioned such that the spindle extends through the through hole in thespacer article, wherein the spacer article is positioned adjacent to andin contact with the rotatable storage article; and (d) a means forsecuring the rotatable storage article and spacer article onto thespindle.
 55. A spacer article comprising: a laminate, wherein thelaminate comprises: (a) two substrate layers; (b) a layer of vibrationdamping material comprising viscoelastic material, wherein the storagemodulus of each substrate layer is greater than that of the viscoelasticmaterial in the vibration damping material; wherein the layer ofvibration damping material is laminated between the two substrate layerswithin the laminate; wherein the laminate has a configuration in partialcross-section which is U shaped; and wherein the spacer article has athrough hole therein.
 56. The spacer article of claim 55 wherein thespacer article has a force retention of at least about 92 percent of aninitial compression force of 1.4×10⁶Pascals applied to the spacerarticle for about 0.2 to about 2 seconds at about 25° C. at about 15minutes after the application of the initial compression force.
 57. Adisk drive assembly comprising: (a) a disk drive, the disk drive havinga spindle; (b) a rotatable storage article positioned such that thespindle extends through a through hole in the rotatable storage article;(c) the damped spacer article of claim 55 , wherein the damped spacerarticle is positioned such that the spindle extends through the throughhole in the spacer article, wherein the spacer article is positionedadjacent to and in contact with the rotatable storage article; and (d) ameans for securing the rotatable storage article and spacer article ontothe spindle.
 58. A spacer article comprising: (a) a substrate, thesubstrate having a through hole, the substrate having a sideways U-shapein partial cross-section, the substrate comprising an upper base, alower base, and a side joining the upper base and the lower base, thesubstrate having an internal cavity; and (b) vibration damping materialcomprising viscoelastic material, wherein the storage modulus of thesubstrate is greater than that of the viscoelastic material in thevibration damping material, wherein the vibration damping material ispositioned within the cavity of the substrate such that it is contactwith at least both the upper base and the lower base of the substrate,wherein the spacer article has a through hole therein.
 59. The spacerarticle of claim 58 wherein the vibration damping material in the cavityis compressed and/or elongated such that its height within the cavity isreduced by about 0.05 to about 75% of its initial uncompressed and/orunelongated height.
 60. The spacer article of claim 58 wherein thespacer article has a force retention of at least about 92 percent of aninitial compression force of 1.4×10⁶ Pascals applied to the spacerarticle for about 0.2 to about 2 seconds at about 25° C. at about 15minutes after the application of the initial compression force.
 61. Thespacer article of claim 58 wherein the substrate is substantially ringshaped and the vibration damping material is substantially ring-shaped.62. A disk drive assembly comprising: (a) a disk drive, the disk drivehaving a spindle; (b) a rotatable storage article positioned such thatthe spindle extends through a through hole in the rotatable storagearticle; and (c) the damped spacer article of claim 58 , wherein thedamped spacer article is positioned such that the spindle extendsthrough the through hole in the spacer article, wherein the spacerarticle is positioned adjacent to and in contact with the rotatablestorage article.
 63. A spacer article comprising: a laminate having athrough hole, the laminate comprising: (i) an upper substrate layer anda lower substrate layer; (ii) a layer of vibration damping materialcomprising a viscoelastic material positioned between said upper andlower substrate layers; wherein the storage modulus of each substratelayer is greater than that of the viscoelastic material in the vibrationdamping material layer; wherein at least one deformation area is presentin said spacer wherein a deformation area is an area of the spacerarticle wherein at least one substrate layer is plastically deformedsuch that the upper and lower substrate layers are touching orpositioned closer to each other than in an area of the spacer article inwhich none of the substrates are plastically deformed; and wherein in atleast 1 vibration damping material layer, within at least a 0.5% area ofthe deformation area, the vibration damping material is non-existent or,if present, has a mass that is 90% or less than the average mass of thevibration damping material layer of an equal area in an area of thespacer article which is not in a deformation area.
 64. A spacer articlecomprising: a laminate, the laminate having a through hole therein,wherein the laminate comprises: (i) an upper substrate layer and a lowersubstrate layer; (ii) a layer of vibration damping material comprising aviscoelastic material positioned between said upper and lower substratelayers; wherein the storage modulus of each substrate layer is greaterthan that of the viscoelastic material in the vibration damping materiallayer; and wherein the spacer article is welded such that the uppersubstrate is welded to the lower substrate.
 65. A spacer articlecomprising: an upper substrate layer and a lower substrate layer; alayer of vibration damping material comprising a viscoelastic materialpositioned between said upper and lower substrate layers; wherein thestorage modulus of each substrate layer is greater than that of theviscoelastic material in any vibration damping material layer with whichit is in contact; wherein the vibration damping material layer of thespacer article further comprises an additive selected from the groupconsisting of fibers, particulates, and mixtures thereof; wherein thetotal amount of additive is about 1 to about 95 weight percent basedupon the total weight of the vibration damping material; wherein theparticulate size ranges from about 0.05 to about 125% of the averagethickness of the vibration damping material layer in which theparticulate is present; wherein the fiber diameter ranges from about0.05 to about 125% of the average thickness of the vibration dampinglayer in which the fiber is present; wherein the load bearing capacityof the additive is at least about 700,000 Pascals.
 66. A disk driveassembly comprising: (a) a disk drive, the disk drive having a spindle;(b) a rotatable storage article positioned such that the spindle extendsthrough a through hole in the rotatable storage article; (c) the spacerarticle of claim 6 , wherein the spacer article is positioned such thatthe spindle extends through the through hole in the spacer article,wherein the spacer article is positioned adjacent to and in contact withthe rotatable storage article; and (d) a means for securing therotatable storage article and spacer article onto the spindle.
 67. Thedisk drive assembly of claim 25 wherein wherein with respect to thelaminate, the layer of vibration damping material comprising aviscoelastic material positioned between said upper and lower substratelayers, wherein the viscoelastic material has a loss modulus of lessthan about 400,000 Pascals, a storage modulus greater than about 200,000Pascals and a loss factor of between about 0.1 and about 0.45 whenmeasured at 1 Hertz and between 25 and 80° C.
 68. The spacer article ofclaim 33 wherein the vibration damping material has a constraining layerattached to a surface of the vibration damping material not directlybonded to the first surface of the base.
 69. The spacer article of claim50 wherein said constrained layer damper has a height such that itranges from being about 102 to about 120 percent of the height of theside having a greatest height on the lower surface of the base.
 70. Thespacer article of claim 51 wherein said constrained layer damper has aheight such that it ranges from being about 102 to about 120 percent ofthe height of the side having a greatest height on the lower surface ofthe base.
 71. The spacer article of claim 49 wherein the spacer articlehas a force retention of at least about 92 percent of an initialcompression force of 1.4×10⁶ Pascals applied to the spacer article forabout 0.2 to about 2 seconds at about 25° C. at about 15 minutes afterthe application of the initial compression force.
 72. The spacer articleof claim 49 wherein the first constrained layer damper has a heightabout 0.02 to about 0.1 mm greater than the height of the side havingthe greatest height on the upper surface of the base and wherein thesecond constrained layer damper has a height about 0.02 to about 0.1 mmgreater than the height of the side having the greatest height on thelower surface of the base.
 73. A disk drive assembly comprising: (a) adisk drive, the disk drive having a spindle; (b) a rotatable storagearticle positioned such that the spindle extends through a through holein the rotatable storage article; (c) the damped spacer article of claim49 , wherein the damped spacer article is positioned such that thespindle extends through the through hole in the spacer article, whereinthe spacer article is positioned adjacent to and in contact with therotatable storage article; and (d) a means for securing the rotatablestorage article and spacer article onto the spindle.
 74. The spacerarticle of claim 59 wherein the vibration damping material in the cavityis compressed and/or elongated such that its height within the cavity isreduced by about 1 to about 5% of its initial uncompressed and/orunelongated height.
 75. The spacer article of claim 48 wherein theconstrained layer damper is segmented
 76. The spacer article of claim 49wherein the first constrained layer damper has a height about 0.02 toabout 0.1 mm greater than the height of the side having the greatestheight on the upper surface of the base and wherein the secondconstrained layer damper has a height about 0.02 to about 0.1 mm greaterthan the height of the side having the greatest height on the lowersurface of the base.
 77. The spacer article of claim 49 wherein theconstrained layer dampers are segmented.
 78. The spacer article of claim19 wherein the vibration damping material further comprises an effectiveamount of an electrically conductive material so that the resistancebetween substrate layers is less than 100 ohms.
 79. The spacer articleof claim 25 wherein the vibration damping material further comprises aneffective amount of an electrically conductive material so that theresistance between substrate layers is less than 100 ohms.
 80. Thespacer article of claim 28 wherein the vibration damping materialfurther comprises an effective amount of an electrically conductivematerial so that the resistance between substrate layers is less than100 ohms.
 81. The spacer article of claim 42 wherein the vibrationdamping material further comprises an effective amount of anelectrically conductive material so that the resistance betweensubstrate layers is less than 100 ohms.
 82. The spacer article of claim63 wherein the vibration damping material further comprises an effectiveamount of an electrically conductive material so that the resistancebetween substrate layers is less than 100 ohms.
 83. The spacer articleof claim 65 wherein the vibration damping material further comprises aneffective amount of an electrically conductive material so that theresistance between substrate layers is less than 100 ohms.